I just recorded a longplay movie in ZSNES 1.42 and it seems there is no way to dump movies using that version.
Is it somehow possible to transfer the movie to ZSNES 1.50 and dump it there? I can't find the movie file though, does ZSNES 1.42 create those?
Movie dumping was included post 1.42 releases. I believe you should be able to dump in 1.50, but there is potential to desync using this method. The movie recording is saved as gamename.zmv.