Your headphones are connected to the laptop, yet its video is silent. The phone in your pocket is also connected. Multipoint lets supported headphones maintain two connections, but that does not mean both devices can play through them at once.
First check that the laptop has selected the headphones as its audio output. Then look at the phone: a media or calling app may still be using the connection even when you hear nothing.
Stop the first app, then try the second
Sony documents a useful example for the WH-1000XM5 and WH-1000XM5SA: a connected device can continue sending a silent signal after playback stops, preventing the switch. Its troubleshooting sequence includes checking that the two-device option is enabled, stopping playback on the first device and closing that app.
Use that as a model-specific clue, not a rule for all headphones. Check your own headset’s multipoint instructions and companion-app settings. Do not end an active call simply to test a video; wait until the call is finished.
Isolate the connection without erasing it
At moderate volume, play a short clip on the laptop, stop it and test the phone. If switching still fails, temporarily disconnect the phone from the headset without forgetting the pairing, then repeat the laptop test.
If one-device playback works, note the exact two-device sequence that fails, such as returning from a call to a paused video. That gives you something specific to troubleshoot before a reset. If it remains silent with one device, investigate output selection and app volume separately.