This is a good question, there are a lot of bad documentaries out there but it is harder to find good ones.

Here are some of the best documentaries that I know of for someone who wants to learn more about the Ptolemaic period. I am using YouTube links for all of them in case you do not want to have to find them yourself.

"Rise and Fall of the Greatest City: Alexandria" hosted by Bettany Hughes. Although it does not focus on the Ptolemaic Dynasty, it tells the history of their capital Alexandria. As such it is a really good introductory documentary, because it has foundational information about the dynasty. I was not sure how I would feel about this documentary but I had access to someone else's Amazon Prime so I watched it anyway. It actually is very informative and generally accurate, and I thought it was entertaining.

The Immortal Egypt series hosted by Egyptologist Joann Fletcher, particularly the episode "Who Were Egypt's Great Invaders?" This episode looks at the great foreign dynasties of Egypt, including the Nubians, Saites, and most importantly the Ptolemies. This is a very important documentary because it gives context for the condition Egypt was in when Alexander the Great arrived, and how the Ptolemies were perceived in light of past dynasties. Once it gets into the Ptolemaic period, it explored the impact and legacy of the Ptolemies. Fletcher actually wrote a biography of Cleopatra, so she's a great guide to the Ptolemaic period.

Historia Civilis did a great episode on "Bureaucracy in Cleopatra's Egypt" which I promise is not anywhere near as boring as it sounds. It actually talks about the way that a line of Greek rulers managed an Egyptian population, where their wealth came from, the legal status of Greeks and Egyptians and what the basic shape of government in Ptolemaic Egypt looked like. I think Historia Civilis is a very underrated history youtuber, his videos are accurate and we'll sources, his animations are simple and clean (read: easy on the eyes) and he is a good narrator.

Extra Credits recently did a series Cleopatra which is fun and easy to watch. I love Extra Credits because they have a really nice animation style and easily digestible segments. Sometimes they play a little fast and loose with facts and repeat less than trustworthy anecdotes, but they usually address these in follow-up "lies" videos which are a bit more historiographical. There are issues with Extra Credits but I still highly recommend them.

Ancient History Encyclopedia produced an episode presented by the wonderful Kelly Maquire on "Famous Female Pharaohs and Queens of Egypt", which includes some Ptolemaic queens.

The Exploress Podcast did an episode on "Arsinoe II: Queenmaker of Ptolemaic Egypt" with Branko van Oppen. If you were to listen to a podcast about any single ruler, I would recommend Arsinoe II or Ptolemy II, because their reigns set the tone for the dynasty, how they presented themselves, their core policies, and their role. It was also during their reign that many famous Ptolemaic institutions like the Great Library, the Lighthouse of Alexandria, and the Ptolemaia festival were established. Although I have not personally listened to this podcast (only because I lack the patience to focus on podcasts), I can vouch for the depth of knowledge and enthusiasm that van Oppen has, he has done some really fantastic research on Arsinoe II in particular.

Lastly, Invicta did an episode titled "Misunderstood Moments in History: Cleopatra's Egypt". Oh boy, the writer/researcher on this one did an OK job, although I hate looking back at old work. Invicta accidentally added some inaccuracies when he edited my script, but we addressed these later in a 2 hour livestream which went into further depth on the subject. It is a decent introduction to the Ptolemaic period, although it focuses on the reign of Cleopatra since the sponsor was Assassin's Creed: Origins.

Since I do not usually watch documentaries because of the time commitment, I am sure there are many other excellent ones out there that I have not heard of.

When trying to figure out whether a documentary is any good, I like to ask myself a few questions.

1. Who made the documentary? (If it is posted by a channel or produced by a network like History Hit, BBC, etc than it is a safer bet than a video by GreatSecretsOfAncientWonder42069. The History Channel is a major outlier because although it used to be great, and still occasionally pits out not awful stuff, it has produced a LOT of garbage in recent years.

2. Sniff test/Does this feel overly sensationalized? If a documentary starts making claims about insane secret discoveries that they are bringing to light there is a good chance that it is hokey. Generally, our understanding of archaeology and history changes gradually as new clues are found. Good documentaries about new discoveries tend to explain what was previously believed, the process of finding and understanding new discoveries, and the reasons why said discovery are important.

3. Who is presenting the documentary and/or who are the guest experts? Here it can be a bit tricky because all documentaries like to hype up their experts, but often Googling them should give a bit of background for them.

4. For YouTube videos, are there sources in the description or as a pinned comment? Most good history YouTubers make their sources known and easily accessible to viewers. This way, you can know where their information comes from and even do your own research on these sources if you want. This is extra helpful for students and people working on projects.

Generally, if you view documentaries with a critical eye, it's not hard to distinguish the good from the bad.

I hope this list helps you!