im not quite sure this is a problem of chrome.... i think its a flaw of shockwave flash.... (we are talking .flv videos right?)
i say this because opera, firefox, IE and even the playstation 3 all 'reload' the file from scratch (and in the case of opera, firefox and IE i can verify they create a new file in this process as well) from the dynamic urls usually associated with flash videos on youtube, and similar .flv based, sites...
chrome may not put a limit on disk cache size which could cause problems but would do so with more than just video sites... albeit at a much slower/less noticable pace.... (i have not tested chrome to verify this)
anyone with more input on chromes cache usage?