Just like movie theaters left the movie business at some points and entered the popcorn business there might be a reason why Netflix couldn't do without those un-skipables previews. Maybe numbers showed that enough previews triggered more rentals ? Which are now absent from naked downloaded DVDs ?

In that time frame (where Netflix was still sending truckloads of DVDs across the country) I don't see how downloading the pirated version of a DVD would be faster than using DVD shrink on the Netflix DVD though.

It was definitely faster. I distinctly remember downloading a ~700MB Divx AVI from Easynews while the DVD was in progress. I don't remember what year but a rough guess was maybe 2010.

Ah, if by pirated DVDs you mean a 700MB Divx then yes I can see how it could be faster. There would need to be a lot of previews on the DVD and a lot of peers for the Divx and a beefy connection (so a recent movie I suppose) though.

If your torrent program supports it[0], you can tell it to download the first chunk (quarter, file, etc) at higher priority than the rest, then watch that while it downloads the second chunk at high priority, and so on (basically streaming, except done right rather than as a way to defraud the user out of their downloads).

0: This is more commonly/obviously supported for torrents containing multiple files, eg a TV show where you can get episode-1.mp4, then episode-2.mp4, etc.