Actually and confusingly, the G# is the 3rd of the scale, which makes that V/vi a little puzzling, but then I haven't seen the video(*).

V/vi would suggest B/C#, i.e.. C#, B, D#, F# which bears little resemblance to the chord shown (G#, C, D#) and which may explain SBM's question. The omitted '7' would have been the F#.

(*) OK, I found the video and the relevant words are "The five of the six", so that V is not the fifth of E, it the fifth of C#, i.e., the fifth of the relative minor of E.

All of which not withstanding, as AudioTrack points out, BiaB just allows it without complaint.

Video here: V7/vi and Resolving Tricks

Jazz relative beginner, starting at a much older age than was helpful.
Kawai MP6, Korg M50, Ui24R, Saffire Pro 40.
AVL:MXE Linux; Windows 11; Win8.1: Scarletts
BIAB2022 UltraPAK, Reaper, a bunch of stuff.