So couple of findings so far :
1 Takes a good 50 seconds to boot
2. Stopping a playing video hangs for around 5 seconds
3. Bookmarks creation forces video out of sync (Rock Pi4 and Bookmarks)
4. Deinterlacing settings seems to be greyed out ?
5. I know Raspberry PI used to use hardware for video decoding with Liebre will Rock Pi 4 have its own HW Video decoding ?