[Highly experimental] Force Core Clocks to be 25% for video playback

Okay so I was roaming Tico's discord server and people mentioned that videos play back better if the core clocks are set to 25% and I swear I was banging my head on the wall literally yesterday trying to fix this issue. First I thought maybe its an MVD issue but MVD hasn't been fully implemented yet.
Added a manual, cheap hook from the frontend - definitely a hack if anything but it kinda works? its still highly experimental and will cause issues, no doubt. Basically if the emulator detects you're playing a video, the core clocks are forced to 25%, and then when the video is supposedly finished playing, it'll reset back to original value.

Test and lemme know pls.