Video player freezes UI when 'Cancel' button is pressed

[taweisse]

When playing an RTSP video stream, pressing the 'Cancel' button freezes the UI for 10-30 seconds. It does not matter if the button is pressed before the video loads, or when it has failed to load. ATAK eventually recovers and can be interacted with again. The issue can be consistently reproduced using the Hello World plugin example:

1. Ensure Hello World plugin is installed and loaded into ATAK on device.
2. Open the hamburger menu in the upper right, and select the Hello World Tool to open the plugin dropdown.
3. Scroll down to Notification Examples, and press Play a Video with Overlay.
4. Press the cancel button before the video loads, or after it fails, which will happen with the Big Buck Bunny stream as of the date of this bug report.
5. Observe that the ATAK UI freezes and cannot be interacted with for some time.

This issue was discovered using a Samsung Galaxy Tab S4 SM-T830, but has been seen on other devices as well, both with the Hello World example as well as a third-party plugin.

The issue appears to be caused by the com.partech.pgscmedia package, for which the source is not available for further investigation.