Coby (Bravis in some countries) MP705 won't play AAC in M4B (iTunes audiobook, renamed m4a, tags stripped) and formats 'Audio Data Transport Stream' and 'Dynamic Adaptive Streaming over HTTP' from YouTube. Any options?
iTunes audiobooks are DRM protected.
You can try using the command line decoder with youtube-dl, assuming it supports forwarding streams to a single stdout stream.
Most simple portable devices struggle with exotic mp4 streams. You can pack files (without drm of course) into more normal mp4 streams using mp4box or many other tools.
Thanks for your replies! Just in case, forgot to add that it plays fine 1-2 sec of such tracks and skips to another, i.e. decodes but then fails.