Hey Cheeaun,
The NI-IMAQ for USB Cameras is a free software driver for acquiring images from any DirectShow imaging device into LabVIEW. If your USB TV Adapter is not DirectShow compliant, then the NI-IMAQ for USB driver will probably not be able to acquire images using it. Just because Windows can detect the USB camera, and the I-Vision software can acquire from it, does not mean that the NI-IMAQ for USB driver will be able to detect or acquire images from it.
The best way then to acquire images from a non-DirectShow USB "camera" is to use the DLL that comes with the hardware, and use the LabVIEW Call Library Function Node to access that DLL. This is kind of like making your own USB driver for the tv adapter. Most often, 3rd party DLL's will return the video data as a 2-D array of pixel data. You can then use the Vision Development Module function called IMAQ ArrayToImage.VI to convert the array of video data into an image data type to be used to display images in the Image Display.
I hope this helps. Please let me know if you have any further questions or concerns. Thanks, and have a great day.
Regards,
DJ L.