Quite I while ago I posted a link to an old TV programma, amd after overcoming some technical problems I can repost the video here.
This one, showing an ensign of the Frisian Schwartzenberg Regiment according to the text, looks like a copy of another plate made for the dutch miitary historian ten Raa. The plates were made late 19th century/early 20th century by a Czech or Austrian historian called Norbert Robitcheck "after earlier plates", so are not originals. (Info from the late Dr Jean Belaubre and Yves Roumegoux). Dr Belaubre was a firm believer in the authenticity of the depicted uniform colours and flags but I still have my doubts.
I this case the Schwartzenberg zu Hohelandsberg banner is depicted wrong as it is turned 90 degrees. You can take a look at Andre Buwalda's website here, for more info on the family.
I also have great doubts about the yellow/black and red/white parts and the Frisian lion is a bit different than the Holland lion. It might be Robitcheck took his info from German Adelsbuche where indeed a very old Bavarian (!) Schwarzenberg Wappen is decribed with black, red and gold. (On google books a lot of Adelsbuche and German heraldry books can be found). Robitcheck did the same trick with the Beveren flag, in which he mashed up the heraldry of the German Bevern and the Dutch Beveren.
So I am not convinced about the authenticity of the flag.
This is an undated painting by the Dutch inventor and painter Jan van der Heyden of the city of Veere, probably 17th century, from the Mauritshuis Collection. This Collection is not accessible through the website of the Mauritshuis but through euopeana.eu (just search with "mauritshuis" and "painting").
Maurits is the dutch equivalent of Maurice, and in this case it's Maurice "The Brazilian", who made his fortune in Brazil, at a certain time a dutch colony. Maurice also had a carreer in the Dutch Army.
Yesterday we talked about William III's guard but it is not quite known that from early 1672 Cornelis de Witt, also had a guard of 50 men, dressed in red coats with yellow lining.
They are depicted here on a "schoolplate". There are other sources like papers who describe them as well, but my source is HSL V, p.314 esp. note 24.