If it's happened without you doing anything, it might not be this, but you could try checking in the Expansions Packs panel under Settings to make sure that the 'Enable Serato Video' checkbox is actually set to enabled.

If Serato Video isn't showing up despite activating it in the panel, it's worth checking a few things. First, make sure the "Enable Serato Video" checkbox is checked in the Expansions Packs panel under Settings. Sometimes settings can get reset or changed unexpectedly. Since it worked on your old MacBook Air, it might also be worth looking into compatibility issues or updates related to your new MacBook M3. Ensure that you have the latest version of Serato Video

If you're having trouble with Serato Video not displaying, first ensure that the 'Enable Serato Video' checkbox is checked in the Expansions Packs panel under Settings. If you're unsure how to enable Serato Video or if the issue persists, you can check the guide for detailed instructions here: [support.serato.com]. This resource should help you troubleshoot and resolve any issues with video activation.