Yeah you can hook your TV to your computer or you can download a program to change the format/container/extension of the file to what ever your TV supports.
Example your file is .MP4 or .MKV and your TV only supports .avi and .divx then you re-encode the file and put it in a .avi format/container/extension. This is a guess ???
You have to use a program to do this you can not simply rename/change the extension.
Try searching there are numerous free programs to choose from some are better than, easier than, faster than others..https://www.google.com/search?q=convert ... =firefox-a