Hi @lodel,
I have tested this template on my side and it runs successfully:
Gain and store video insights video uploaded to OneDrive (Part 1):

Gain and store video insights video uploaded to OneDrive (Part 2):
And the video in the Indexer can play normally:

The template has two parts, there have two Flows you need to create, part 1(Flow 1) and part 2(Flow 2). After you create part 2 Flow according to the document, you should save it, then copy the URL is created in the trigger automatically, then paste it in the Callback URL in the part 1 Flow.
The error about the uploaded video may be caused by the upload process, you can have a try to upload it again to check the video whether could be played successfully.
Best Regards,
Community Support Team _ Lin Tu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.