Well now I’m just thinking about why the movement of the strings is so noticeable in that video. To my (tone-deaf) ear it sounds like the note whose string is most nearly frozen is B3, so I guess it makes sense if the video was shot at 25fps, meaning that string is vibrating at close to the tenth harmonic of the frame rate (246.9Hz). I believe 30fps is usual for phones (?), but 25 is a common option for SLRs.
I was wondering if you’d need to do something special to get the moving-strings effect, but thinking about it, I guess this is the norm for modern camera sensors, because they’re so fast that the “shutter” will only be open for a tiny fraction of the length of a single frame, so it’s like using a strobe light. The frequency difference between two semitones is only 6%, so any normal music is likely to have notes that are close to an integer multiple of the frame rate. It also occurs to me that, since many cameras can now shoot 1200fps or faster, if you shot a stringed instrument in slow-motion you’d easily be able to see the strings move in real time. In fact, if you didn’t want to see the strings moving, you’d probably have to shoot in candlelight.