According to several forum pages (forum 1 and forum 2) where your problem has been discussed, the thinViewer program was discontinued. Also, according to officials, there is no way to view your TMI files anymore.
To solve your problem, you can use Software Informer database to find a converter that can work with your files. By doing this, you will be able to convert the TMI files to a common format like AVI or MPEG that can be used with a regular video player.