Ooh! Tantalising glimpse at the Don Donald title card in terrible quality without the rest of the opening titles and no end title. Although is this definitely the original title card? I'd guess so, but it could possibly be something created for a home movie version.
LuckyToon, when you say you "know for sure" that those three cartoons originally opened with Mickey titles, have you actually seen original prints? In Merritt and Kaufman's Silly Symphony book it is mentioned that 'Don Donald' was classified as a Mickey Mouse cartoon for book keeping purposes, but on screen it was billed as Donald Duck cartoon – the first in the series.
I think the BFI may have a print of Don Donald with original titles, but I can't verify this. I don't know if Modern Inventions and and Donald and Pluto are known to exist anywhere with original titles.
Thanks for posting the video, kazblox.