Hi @Bibi1,
Thanks for raising this concern directly to us, and welcome to the Roku Community!
If the issue persists on one channel after attempting the troubleshooting steps and videos from other channels play fine, contact the channel provider's customer support team to report the issue and get help. Channels on Roku are maintained by the channel developers themselves. In this case, there's likely an issue within that specific channel that needs to be addressed with an update from them.
Please let us know if there's anything else that we can do to assist you.
Kind regards,
John
John
Roku Community Moderator