I have not seen the videos in question (and there appears to be quite a few of them)-- are there any specific claims made in them that you have questions about? I have written previously on the traditions of holy war and sacred violence that underpin the crusading ethos as well as how the seizure of Jerusalem was rationalized as an act of defense by early 12th century ecclesiastics. Outside of that, you may want to try your hand at some of these other answers that tackle the subject, particularly with regards to popular claims about crusade. It's a fairly popular topic:

• I received this article today in an email, it's essentially denouncing Islam and justifying the crusades. Can someone tell me how legitimate this is?

• I saw this article about the Crusades posted on Facebook. How accurate are the bullet points?

• Given the recent uptick in Jihad versus Crusade comparisons, i've seen this image a lot, what does it ACTUALLY show?

You might also want to check out the FAQ section Motivations for the Crusades, in particular the post:

• Who started the Crusades? (Each one)