According to what I saw in the video, its not silver. Forget the wiping, it should show a pretty red color for high grade silver, like coin silver or sterling, in just a few seconds.
I would suggest to take a silver dime or something of melt value only and you will be able to compare. The acid will leave a stain on the coin however.
Now the only thing good I can think of is that it may have some low percentage silver because basically you would be testing the base metal. But generally speaking yellow is a bad sign. Silver should be a pretty red but changing to maroon or even brown for lower grade silver. Not yellow. Yellow usually means tin, aluminum and lead I believe.