Hello everybody!
Does anyone happen to know if this particular theme is available for download somewhere? (see video below)
Thanks a lot.
This is the old default theme from Renoise 1.8 (or roughly around that time).
If you really can’t live without this particular theme, you can simply download an old Renoise demo to get it, or download the full version from Backstage.
Once you have the old version installed, you can load the theme .xml into the latest version of Renoise. There may be some tweaking and fine-tuning required to make it look perfect, since quite a lot has changed in the 5 years from 1.8 to 2.8 
Oh, great! Thanks, dblue!