I have been using the GUI (right click => compress) to try and compress a .tar containing 3 videos totalling 1.7gb (.H264 MP4s). gzip, lrzip, 7z etc. all do nothing to the file size and the compressed folder is also 1.7 gb.
I then tried running lrzip from the command line (in case it was a gui problem), and used the -z flag (extreme compression), and this was my output.
As the compression ratio shows, the actual size of the compressed folder is bigger than the original! I don't know why I am having no luck, lrzip in particular should be effective according to random reviews I have read and the official docs (files larger than 100mb, the larger the better) - see https://wiki.archlinux.org/index.php/Lrzip
Why can't I compress my files?