FYI:
For me using the latest Safari Technology Preview - Release 239 (WebKit 20625.1.8.19.1) or standard Safari - version 26.3.1 (20623.2.7.18.3) on Intel Mac OS 15.7.4 (24G517) some videos now playback as a solid green block. Audio appears to be fine. Video works fine as expected in latest builds of Chrome, Firefox, Edge, on the same device.
Example video where this occurs: https://www.sexlikereal.com/scenes/liquid-fantasies-2-82399
Unclear if it's just that specific video (vs something with the new player), as I swear I had the same issue with a couple other videos recently and thought it was a glitch (as I typically download versus play in browser) until just now when it happened again. I had noticed the player had changed, so I tried it in a several other browsers with the results above, then came to the Forums to check if it is perhaps a known issue, and ran ran across this thread.
If I find others, I'll report back as the above is easily repeatable from my end. Will also try checking it in Safari on Apple Vision Pro as well.
UPDATE: Found a common thread and confirmed I am not misremembering. I found the same issues on three of the most recent CyberWorldVR releases: 82020, 81315 and 81004 - that's in addition to 74730 I noted above. There may be more, but hopefully this helps narrow things down.