They had us in the first half, not gonna lie.
Based on the comments available online, it seems this lady has a hearing impairment and really enjoyed feeling the bass of the music. She was trying previously to use sign language to communicate with them which led to some initial confusion and nervous laughter (which is where the 'It's not funny' comment by her may have come from). Thankfully, this video takes a much better turn than I initially expected as granny starts pumpin' her hands to the beat.
Many of Reddit have dubbed her 'Carol' - a wholesome antithesis of the 'Karen
' trope. In a world full of Karens, let's all be more like this Carol.