Emulator

Game Name:
Sonic Riders: Zero Gravity (US release, though the region probably shouldn't have any effect on this bug)

Game ID:
RS9E8P

MD5 Hash:
8152b6ab8109a0144a1c9d8779a40aa6

Problem:
The game features prerendered video cutscenes at several points in story mode, as well as when booting up the game. However, when emulated, the cutscenes will not render at all, only playing the sound that comes with them and leaving a black screen instead.

How-to reproduce:
Simply open up the game, the SEGA logo and an intro cutscene should immediately attempt to play, only playing the corresponding audio instead.

Emulator version:
5.0-6309 (latest development version as of writing this)

Here's a 3-second (180 frames) fifolog taken around the beginning of the introductory cutscene (screenshots would be pointless as it's just a black screen):
https://www.dropbox.com/s/1sfqwa1dvc7ltt4/rec.dff?dl=0

PC Specifications:
CPU= Intel Core i5-6500 @3.20GHZ
GPU= NVidia Geforce GTX 970
OS= Windows 7 Ultimate, 64-bits
RAM= 16GB DDR4

Extra Info:
I have tried several graphical configurations and INI tweaks, to no avail. I have, however, noticed that going into the graphical settings while the game is open and a video cutscene is playing, and then changing the texture cache accuracy during that cutscene, causes the game's window to update to the current frame in the video cutscene, getting stuck on that frame instead. Changing that setting to "Safe" and rebooting the game does nothing to fix the issue, however.