1. Add ability to choose between Trailers and Teasers.
Many People just want a small Teaser, instead of a Full-Length-Spoiler
2. Proper Qualities
Sometimes they are full length HD, and a lot of times they are potato quality, random TV spots/teasers instead of trailers, foreign versions, and sometimes those “new on DVD” promo trailers from like early 2000s.
This includes proper support
This could be done by implementing TrailerAddict for example.
But another problem is foreign language with traileraddict it seems. While themoviedb.org has option to choose foreign language trailers.
TrailerAddict

