He could donate to the Gimp devs or invite his followers to do so.

All of these videos feel like "paying with exposure" to me. No one talks about the struggle of very small teams developing software in their free time, with very few resources. Someone who doesn't know about FOSS could think they have all the resources a big company has.

If you're rich like this guy and want to dump on FOSS projects, pay for the admission first.