Ditto for me.
Youtube made some changes to their website on Tues/Weds that broke some 3rd party applications. Looks like it has also broke the Humax app. Guess we will have to wait for Humax update the Portal.
VLC should play the files OK on Ubuntu.
I see from another post that you have installed the custom firmware and I assume that you have installed auto-unprotect ?
Are you using FTP to transfer the files ? (FTP will not unencrypt the files as they are copied over to the PC)
What happens if you...
If you install custom firmware it is possible to watch both HD & SD recordings from a Laptop but you have to decrypt the HD programmes first. The following guides may point you in the right direction.