I see 250+ people clicking on the "I have this question too" button - to Blake's note.
But .. for documentation sake .. here are further details.
0) I'm on the latest and greatest O/S version 11.2.2 (20D80)
1) Reloading the web-page shows an annoying and persistent animated "loading" circular-arrow, right in the middle of the video.
2) To get rid of it, i have to quit Safari and restart again.
3) Note: DisneyPlus website's does a good job of bringing me back to the same scene, when I restart the browser.
4) And ..
.. all of the above will only last a few minutes.
5) Then "rinse and repeat" endlessly.
There are a couple of times, the memory warning is followed by the Safari window "restarting" (for lack of a better word) all by itself. That only "automates" step 2 above.
NOTE: This started after I very recently upgraded the MacOS. This problem did NOT exist FOR ME, with previous Mac-versions.
NOTE: I quit everything except Safari and Finder. Rebooted for good measure. Still exact same experience!!!!!!!!!!!!!!!!!!!!!
Am going to try giobellato's suggestion, and will update after a few weeks.