Video glitching, need help

I’m using Cubase 11 on Windows 10. When I play video at quarter size it plays perfectly. But when I go to full size or fill screen, the video intermittently freezes and then catches up. It’s very glitchy. Anyone have any ideas?

It’s not a new issue, I heard many users reporting more or less the same.
I use a hardware based video playback so in my case I have never had such problems, plus, I always convert any video I get into ProRes Proxy or ProRes LT for smooth playback experience.
May I ask what video formats are you using?
Regardless, you may want to avoid full screen playback and size the playback window almost as full size but not completely. As far as I know, it happens more often with nvidia graphics cards then amd.

I typically get H.264 1920x1080 23.98 fps, mov files. Had the same issue with an H.264 1920x1080 23.98 fps mp4 files. Had the same issue with an Avid DNxHD Codec 1920 x 1080 23.98 fps (I have the DNxHD add on installed).

I’ll try converting to ProRes Proxy or ProRes LT and see if that fixes it. I do have an Nvidia graphics card (GeForce GTS 950)

It might not be the case for you but I found mp4 files freezing and not playing back smoothly if the video bit rate is too high.

Any kind of h264 is a bad format to work with, doesn’t matter if it’s wrapped in a mov or mp4 container.
That being said, I don’t think your problem is mainly the file format/codec, it certainly may make it worse but will not solve the problem if you work with DNxHD 36M or ProRes Proxy.
As far as I heard it has something to do with the nvidia drivers, and there are some users reporting that a specific (older) driver solved the problem for them, but I don’t know which specific driver that is.
The safe bullet proof action is to move to hardware based playback such as Blackmagic design Intensity Pro, but that will also force you to have a dedicated TV set that will accept the Blackmagic HDMI output.