i have been through a multitude of players and it seems quicktime is the only one that does step forward and back frame by frame properly. Also quictime seems to have a finer level of control than other playeron the timeline in general, and also it doesnt go black at the end of a video, it keeps the last frame. So yeah, its a shame there isnt a player that opens more file types that is as good as quicktime, but maybe it worth looking up about if there is any way to expand what quicktime can play somehow. it does open standard avis though, thats not bad. like this… http://perian.org/ (its only for mac) as then you could just open stuff in quicktime and chop it down in there.
what i find best is if you have a mozilla add on called download helper then if you can locate the clip on youtube you can download it. sometimes you get the option of mp4 which opens in qucktime, otherwise its flv, but if its a short clip it must be easy to convert