I don't know of any published information regarding the availability and use of video codecs for export with the 64 Bit version.
The fact that it is not a "true", but rather an optimized for, 64 Bit piece of software makes it difficult to pin down just what does or does not work with it.
For most professional video uses the Uncompressed AVI and image sequence export options work quite well. The MPEG option is good enough if you only need something done for the Web.
If you really need a special codec for a job then it's best to export the video using the 32 Bit version.
Who knows, maybe version 6 will offer more choices when it is released sometime later this year.
Gerry
System: Win 10 Pro (21H2), Asus X99-E WS, CPU i7-5930K -3,5 GHz, 32 GB DDR4 2666-16 RAM, NVidia GTX 1080 Ti GPU - 11 GB VRAM(Driver Studio-536.99), Samsung 850 Pro 512 GB SSD, 6 TB HD storage.