Hi Andreas, sometimes Vimeo can be naughty. Non-pro accounts convert everything to MPEG-4, but Pro accounts, like mine, should keep the original format. BUT sometimes it renames the file extension, especially when downloading via IE.
So try downloading the file via Firefox to see if the original MOV file extension is preserved. If not, try simply renaming the file to MOV, as the data itself may be the same - the original file measured 172MB, so if the one you downloaded is the same size, it should be the same file.
As for Premiere, you may need to download a codec for it to properly handle Motion JPEG. I needed to do this for Nikon's bodies and found the Main Concept Motion JPEG codec worked a treat. I also found that having ffdshow on my system really mucked things up for Premiere, so if you have it, you may want to uninstall it.
http://www.mainconcept.com/site/prosume ... n-797.html