Hey there MohamedCiise,
Thanks so much for using Apple Support Communities.
We want to help figure out what might be going on here. Have you tried downloading that movie before playing it? If not, we would recommend giving that a shot. If you have downloaded it already, try deleting it and then re-downloading it to see if that may help. Downloading a movie removes the need to rely on your network and can weed out any potential network issues that could be causing this. This article goes over that information: Get shows, movies, and more in the Apple TV app on iPhone - Apple Support
From that article:
Stream or download content
Content from Apple TV+ and Apple TV channels play in the Apple TV app, while content from other providers plays in their video app.
1. Tap an item to see its details.
2. Choose any of the following options (not all options are available for all titles):
* Watch Apple TV+ or Apple TV channels: Tap Play. If you’re not a current subscriber, tap Try It Free (available for eligible Apple ID accounts) or Subscribe.
* Choose a different video app: If the title is available from multiple apps, scroll down to How To Watch, then choose an app.
* Download: Tap
. You can find the downloaded item in your library and watch it even when iPhone isn’t connected to the internet.
We hope this does the trick for you!
Cheers.