Hi AustinBarnum,
Thank you for reaching out to Microsoft Community.
How about other video formats that is saved/downloaded on the device, does it have the same issue?
Did you install iTunes app through the Microsoft Store app?
If yes, please run these steps on your Surface Pro X then try to check again if issues persist:
1: Run Surface Diagnostic Toolkit and check Windows Update
2: Run System File Checker Tool in Windows 10
3: Get updates on apps and games from the Microsoft Store
If this answer your question, we highly encourage you to inform our Community by clicking on Yes or marking my post as an answer. This will help other members who may have the same issue as you. Otherwise, don't hesitate to update us so we can further assist you.
Kind Regards,
Marrion Y.