FWIW - in the the YouTube video Saby automatically worked around the problem, probably without even realising it...
Where the transition is pasted is determined by what clips are selected prior to right-clicking and choosing Paste All and not by the position of the mouse. So, to paste the copied transition onto one or more clips, select them, then right-click anywhere in the timelne and choose Paste All from the pop-up menu
Notes:
- The transition(s) will be pasted at the start or end of each selected clip according to whether the original transition was created as an "out transition" (dropped to the left of the join between 2 clips) or as an "in transition" (dropped to the right of the join between 2 clips)
- The pasted transition(s) will be centre-aligned, regardless of the alignment of the original transition (IMO a bug - but only important if you're using the old "overlap clips" method of adding transitions)
HTH
Richard