I've always avoided watching Yesterday's Enterprise on dvd or whatever because I felt that the introduction of Sela in later seasons trashed it completely. Watching it again on the Alternate Realities collection, and listening to David Carson's excellent commentary, just makes me angry all over again. It's such a beautiful episode, so perfect--why oh why did they have to introduce Sela? Who's bright idea was that? Tasha's second death was worse than her first in some ways, according to Sela's story!