Within the nightlys, what's the difference bezween the tree win64 vs. win64_ffmpeg3?
Which version to use resp. to use for which purpose?
win64_ffmpeg3 is transition in progress towards update_ffmpeg_3.0.2 (still work in progress): developer activity (https://github.com/mean00?tab=activity)
Like win64 has for now not the png alpha support (Applying Combined filter, png logo with transparent background (http://avidemux.org/smif/index.php/topic,16829.msg75151.html#msg75151))
If you're doing plenty of conversions on daily basis stay with win64, if you're in for surprises go with win64_ffmpeg3, more testing and discovering ;)
Thanks a lot for this clarification :-)