I've never really had a problem with them; they're not all that worse than a typical textbook. Which means that there is a lot of nuance missed because of the over-simplification of some complex subjects (such the Silk Road or Atlantic slave trade). However, as a general primer, it is not bad at all; short, animate to keep a viewer's attention, and light hearted in general. I'd recommend them for people who don't know very much about history and want to get a jump on high school (or perhaps Freshman college) history.

The only really crap episode is the one that's simply an out of context list of Civil War battles. It belittles military historians and is completely useless in understanding the topic.

I'd also like to ask if any are really worth watching? They seem kinda biased from what I've heard.

On the Russian history video he claims that most scholars believe the founders of Kievan Rus' where people who migrated from the area around Black sea. He throws away the theory of Varangians simply by saying that Russian today sounds more Slavic than Swedish. Kind of odd, especially since the Vikings would most likely assimilate to the local populations (like Rollo in France). Then leaves the question there.

In the fall of the Roman Empire-video he never says how it finally fell and who it fell to.

Nitpicking, overall good. However he simplifies many things.

I prefer academic lectures on video. YaleCourses has a YouTube channel that has the entire lecture series for several history courses. There are also links for downloading syllabi, handouts, etc.