I've tested the US and EU versions Interactive Demo Disc v1. While the US version has consistent video slowdowns, the EU doesn't.
I've also tested Ribbit King Plus (which just contains a lot of little videos) video stutter as well. (US version tested)
I'm wondering if there is a syncing problem or false default clock-speed that causes the stutter for NTSC(-U) emulation?
Maybe it's something else. Just the first thing I came up with.
It's weird that it occurs just in the US version of the Interactive Demo Disc v1.
I haven't opened an issue in the issue tracker yet because I wanted to contact you first.
Thank you!

Try upping the Emulated CPU Clock rate slightly and seeing if the stutters go away.
(07-27-2018, 03:32 AM)JMC47 Wrote: [ -> ]Try upping the Emulated CPU Clock rate slightly and seeing if the stutters go away.
Done.
103%:
Interactive Demo Disc v1: Gets much better
Ribbit King Plus: Fixes it completely, though crashes occur during the videos.
300%:
Interactive Demo Disc v1: Perfect, even freezes are eliminated
Ribbit King Plus: Changes nothing compared to 103%.
Do you have a log of the crash?
Unfortunately not. Is there a way I can create them?
Enable all logs in the configure log menu (view/Log configuration) and open the logging window and see if it says anything.
The game crashed 3 times in 10 minutes, before the logging. I tried it now for 2 hours and nothing happened. I started restarted dolphin after the crashes so there wasn't a problem with the overclocking. "Ribbit King Plus" didn't even stutter anymore...
Interactive Demo Disc however did. Some details about that one:
The game is running at a consistent 60 FPS and 60 VPS while stuttering.
The stutter is close to completely gone when overclocked at 103%, though the Waverace video will hang at the exact same point in time.
The stutter is completely gone when overclocked at 400%, the Waverace video won't hang.
I honestly can't tell whats going wrong... I hope you can tell me more.

Yeah, I can tell you what's going on - our CPU timings are too slow for some actions and it causes the game to freeze.
(07-29-2018, 03:47 AM)JMC47 Wrote: [ -> ]Yeah, I can tell you what's going on - our CPU timings are too slow for some actions and it causes the game to freeze.
Oh, thank you very much! Is there a fix for it planed before 6.0?
There are no specific plans unless somebody wants to take another stab at improving our timings (very, very non-trivial)