How to see previews of old quicktime movies (old codec)

Since I updated to Yosemite, the .mov previews in Finder no longer show up for videos with an older codec. (When I double click the video, it starts a conversion process.) Is there any way I can see previews of my videos without needing to convert them all? Even if there's a software I can download to see the previews, that is fine. It's too much work to convert all of the videos to see what they are.