I posted this in the general section but thought I'd make it official here.
I don't see the need for having to put each movie in its own folder just to have trailers. Plex only plays 1 trailer for a movie anyways so how about allowing for a default trailer to be placed along side the movie and only require the folder structure for extras, which could also include additional trailers. Most people won't have extras so this would have the lowest impact.
Example without extras
Movie #1 (year).mp4
Movie #1 (year).en.srt
Movie #1 (year).trailer.mp4
Movie #2 (year).mp4
Movie #2 (year).en.srt
Movie #2 (year).trailer.mp4
Example with extras
Movie #1 (year).mp4
Movie #1 (year).en.srt
Movie #1 (year).trailer.mp4
Movie #2 (year)\Movie #2 (year).mp4
Movie #2 (year)\Movie #2 (year).en.srt
Movie #2 (year)\Movie #2 (year).trailer.mp4
Movie #2 (year)\Alternate ending-scene.mp4
The .trailer. file is what gets shown automatically or when you hit the play trailer button. Right now, the extras need to be played manually anyways and no need to include the default trailer in the list with the extras. The automatic extra feature just uses links so not having a folder structure wouldn't impact that either.