Hi there ceciliabal,
Do you notice the same issues when watching videos in other apps? We want to see if this is specifically happening in one app or multiple apps.
Also, if you haven't already, you can see if restarting your iPad may help. Restarting can refresh the software on a device, which can sometimes resolve unexpected issues. If needed, below shows how:
How to restart an iPad without a Home button
1. Press and hold either volume button and the top button until the power off slider appears.
2. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
3. To turn your device back on, press and hold the top button until you see the Apple logo.
Those steps are from this article: Restart your iPad Please let us know how that goes or if you've already tried restarting.
Take care.