Hello @Flubs,
Welcome to the Roku Community!
Thank you for your post. We appreciate you taking the time to reach out to us about this. To confirm, you can indeed cast any videos from your laptop to your Roku device.
For more detailed troubleshooting, please visit our Support page, where you will find instructions on how to screen mirror from your phone, tablet, or computer to your Roku streaming device.
We hope you find this information helpful.
Thank you,
Rey
ERey.
Roku Community Moderator