laptop usb stick doesnt work on TV

^ I think some of the new TVs are starting to add USB ports in addition to (or in-place off) Flash card port.

Most likely it is the type of format ( the extension ) the video file is in. PS If the file is a audio file That would explain it).
Example The files on a dvd are in a .vob format, other types can be .mpg .mp4 .wmv .avi .mpeg ect

You will need to check the manual for the TV to see which types of files it can read. No manual, then go to TV manuf and download the manual. Or google the TV model Number and look for specifications.

For instants if your TV can read .mpg and .wmv BUT your file is a .vob or a .mp4 then you will need to convert the unsupported format to a format that can be read by TV.
.. Just google convert (Non-supported) to (Supported) - convert VOB to Mpeg