Hi Lanky Lad,
Toggling the Video Sync option within the SoundTouch application may resolve the issue you are experiencing regarding a delay between the audio and video on the SoundTouch 300. This is explained in the pinned post linked below:
If you open the SoundTouch application, go to Menu>Settings>Speaker Settings>SoundTouch 300>Group Settings>Video Sync and turn this option ON.
Here is a brief description of how the Video Sync option works:
Keep in mind that this feature is also in beta and that there may be some limitations or performance issues due to this.
Let us know how the above goes! Thanks!
The purpose of the video sync option is to account for the inherent delay that is created by rebroadcasting the audio wirelessly. At this point, you may not be able to have multiple rooms playing video audio perfectly in sync but we're always working to improve the feature.
Hope this helps. Thanks!