Diagonal movie playback issues on iPad screen after minor fall

Your iPad appears to have a display fault. The crack across the screen (or the screen protector that you have installed) indicates that the iPad has suffered a significant drop or other trauma at some point.

As is, the iPad will likely require repair. At the very least, the iPad should be assessed by an Apple technician at the Genius Bar of your local Apple Store or Apple Authorised Service Provider:

Genius Bar Reservation and Apple Support Options - Apple

For practical purposes, in lieu of repairing and returning your own iPad, Apple usually exchange the iPad for a renewed/refurbished iPad of the same model and specification. The cost of the exchange is the same as would otherwise be charged for repair. Unless you have benefit of an active AppleCare plan, an out-of-warranty repair while expensive will be somewhat less than the cost of a replacement iPad.

As for out-of-warranty repair costs, Apple offers a fixed-price price repair. You can verify eligibility and cost for your region/country here:

iPad Repair & Service - Apple Support

If you have an active AppleCare+ plan, the cost of repair is reduced to a small excess/deductible fee.

You're very welcome.