So far, my car is the only thing I have to pair my phone with so I don't know if it's the car or the phone. But, I've only experienced this problem on 4.4 roms. 4.2 was fine, no audio lag at all. Every single 4.4 rom I've used has this problem (cm, aokp, pa, slim, pac, and stock).
The only patch I can think of for movies is to find a player that can allow me to offset the audio (like VLC on Windows does), but I haven't found one that supports that.
Does anyone else experience bluetooth audio lag or delay? When my n5 is paired to my car (2010 Mazda 3), my music doesn't play through my speakers until about 3 seconds later. Audio for movies and videos and games are the same way, so they're out of sync. If I run the Audio Router app (forces audio to be played thru mono "headset mode" [not sure if that's what that's called]) then the lag/delay disappears and everything is fine, except that the audio is now playing at the lower headset bitrate and is mono.