this may seem like a weird question but can an mkv contain multiple video streams of different lengths? the reason i am asking is because there are a lot of movies with alternate endings, unrated version, extended versions, and such. i seem to recall, and correct me if i am wrong, a lot of dvds and blu rays have options to play, for example, the theatrical release or the unrated release and instead of having an entire copy of each version of the film on the disc, a lot of times the extra scenes are just played or inserted when they are supposed to. is something like this possible in mkv yet? this would save a lot of space on movie likes the lord of the rings series.