For some reason it seems to work just fine if you just rename the video file on the hard drive from *.mts to *.mpg (change the file extension). Just rename it, then relink the file in your project to the "new" renamed file. Just to clarify that it may not be necessary to change the file format itself, just the filename.
The same solution worked for some .mp4-files that were causing the same problem in my case, renaming them to .mpg solved the problem.