Since the support of youtube video's with the [youtube][/youtube] is bugged if you post more than one video per post, i wrote this to make it more clear.
What you do is put a youtube link between its tags, ex:
[youtube] https://www.youtube.com/watch?v=4ItqVgaTIjI [/youtube]
This (should) transform into..
[flash(425,350)] https://www.youtube.com/watch/v/4ItqVgaTIjI [/flash]
So its quite simple to code the tags yourself if they are buggy.
?v= changes into /v/ which links directly to the video itself, try it out.
Hope I've helped.