Disappointing.
The slogan on their page ("Committed to you, your privacy and an open Web") sounds hollow when considering this and their recent support for DRM.
That means they actually need donations for the foundation to run (but its not 800 employees so its much less money). Legally you can't fund the Foundation with the Corporation money - since that would make 2 Corporation and zero Foundation then :)
I don't know if the opposite is possible (send donations from Foundation to the Corporation) but I suspect it has the same problem/effect.
The Foundation is the sole owner of the Corporation. The Corporation pays dividends to the Foundation.
Now the amount of those dividends can't be too much if the Foundation wants to keep its nonprofit status. "Too much" is determined by how much people donate: the restriction is on fraction of money that comes from non-donations.
I'd love to support Mozilla as much as possible, but no way I'm keeping the default Google-search when you have stuff like DDG around.
Hopefully me wanting privacy doesn't impact Mozilla's financials too hard. Firefox + DDG only seems like the most natural combination: both are powerful and privacy-centric.