Red bars, yellowing, and pixelated output from Premiere
This is extremely well documented in the Adobe Premiere forum.  Premiere Pro is not fully compatible with El Capitan (10.11).  The work-around is to disable the GPU by selecting "Mercury Software Render", which will remind you why so many people hated doing digital video before GPU cards existed.

The situation is a mess.  Adobe has apologized, is working on a fix, and has no idea when Premiere Pro, or an update to 10.11, or both, will result in a working system.

The other work-around is to back-out 10.11 and downgrade to Yosemite.