There are two (related) issues I want to talk about here. The first was already raised in the V19 testing thread, but is still outstanding; the second I haven’t mentioned before; but there is some important interaction between the two.
Test clips here: Dropbox - Deinterlacing test patterns - Simplify your life
Start by whitelisting both 1080p/25 and 1080p/50. Now play the Sherlock clip. It starts playing at 1080p/25, and looks like it’s playing in slow motion. After a few seconds it switches to 1080p/50 and starts playing incredibly fast. Then the speed settles down, but motion is extremely jerky. You can work around this by de-whitelisting 1080p/25 - so long as it starts playing at 1080p/50, it seems okay. (There are some deinterlacing errors, but that’s not what this thread is about - motion, at least, is fairly smooth).
Now, again, make sure 1080p/25 and 1080p/50 are both whitelisted. Play the Planet Earth clip. Pause it, set the deinterlacing to Off (it’s a VC-1 video so you have this option), stop playback, and then play it again. The whole clip now plays correctly at 1080p/25 and the camera motion is smooth pretty much throughout the whole video.
Now de-whitelist 1080p/25 and play the Planet Earth clip again (with deinterlacing still set to Off - it will remember from last time so you don’t have to set it again). It plays at 1080p/50, but now the motion is jerky. It’s not actually skipping frames, I don’t think, but the effect looks rather like that.
EDIT: The jerkiness on this clip doesn’t always show itself. I’d say it happens about 50% of the time.
So, you have to de-whitelist 1080p/25 to get the Sherlock clip to play correctly; but if you do that then the Planet Earth clip won’t play correctly with deinterlacing set to Off. (Setting deinterlacing to Auto-Select makes the Planet Earth clip play smoothly at 1080p/50 but reduces picture detail).
Some logs of me following the above procedure: https://paste.osmc.tv/purexodayo