I'm new here and hence there's still some ambiguity to remove.
Well, me and some pals, we are working on a project called "Filmschwätzer" (losely translating into "movie gabber" which plain and simply will be kinda the German equivalent to "RiffTrax" (the web-based successor to "Mystery Science Theatre 3000". This means, we watch movies together, comment on the action, point out notable scenes, dialogues or mistakes, provide trivia and altogether run the whole picture down. We record and edit all the claptrap, compile it into mp3 audio and put it online for the public to download and sychronize it with the corresponding movie. How exactly they do that is none of our business, we only provide the audio commentary and the user has to come up with his very own copy of the movie. Hence we can avoid any legal issues. Other than "RiffTrax" we'll provide our audio entirely for free, funding our site via on-screen Amazon ads. Nothing special here.
To get to the point: Every now and then we will release short video trailers to promote our site. These trailers might contain audio samples I've taken from this site. Now I don't want to put any credits into the video itself, because this would ruin the intended visual aesthetics. Does it suffice to attribute to the creator in the file's properties section? Or does the attribution have to be applied within the video itself? I guess, on streaming platforms like YouTube it should be enough to put credits into the corresponding info box, right?
I personally don't think the attribution has to be in the video, but to be found close where the video can be watched. Compare to audio only, if you make a music track with freesounds, you won't add a bit of spoken word at the end saying: "this track contains sound x from y and sound q from z", you simply add some text to wherever the track is, like text in a description field or a legal section in a cd booklet.
Yup, sounds right to me. Thanks. You know, legal stuff can become rather confusing if you live in a country like Germany. I believe we have pretty much the worst bureaucracy in the western world...
at the end of the video, do a text 'credits' part for a few seconds.
Well, didn't need a lib sound at the end. But I'll definitely come back here for further needs.