Converting .trec files to .vlc format.
Converting TechSmith Recording Files directly to a VLC Playlist (.trec to .vlc conversion) is, per se, not possible.
You will first have to convert your TREC file to a format supported by the VLC Media Player, for instance MP4. To do so, your only option is using Camtasia itself.
You can then simply add your .mp4 file to a VLC playlist, which will generate a .vlc file.
A screen capture and video editing software