In my experience with this issue, Flash Player is experiencing some kind of problem to handle several video sources (which may not be your case). In my computer I have several video sources, and somehow it seems that Flash Player can reach the TV Tuner but is having problems to acquire images from the USB devices.
In order to solve this problem I have tried two tricks that I share to you not as a solution for your issue but as an alternative. The usage of the FlashCam Project or the Webcam Studio. Both them will drop a virtual device into your Flash Player device's list which will be easy handled.
In this answer: Flash crashes on enabling webcam I have previously documented this situation and I hope you find it useful, pasted here for your convenience:
Based on my personal experience when using the Ultimate Edition
DistroPlayer, fully documented here:
and information that can be reached here:
https://bugs.adobe.com/jira/browse/FP-204, you can use The Flashcam
Project in order to gain access to your webcam via Flash Player.
I have tried this both in Firefox and Chromium/Google-Chrome and it
works like a charm but I continue experiencing some issues with the
stability of the Flash Player when it tries to gain access to my TV
Tuner instead of the Webcam itself.
Another temporal solution that I find useful is the usage of the
WebCam Studio for GNU/Linux, which will drop a bridge between
your physical webcam and a virtual webcam that can be seen and managed
by Flash Player.
However, you may experience some issues when using both these tools,
anyway it's worth than expecting Flash Player to do what it seems it
Give it a try, and please inform how do you manage this issue. I am
yet interested on having the experiences of other people in order to
fix my TVTuner/Webcam crashing issue.