Firstly, we note that an electron beam coming towards the CRT screen is equivalent to a conventional current moving towards the back of the CRT.
Secondly, we note that if the electrons are moving directly towards the north pole of a magnet, they should see a somewhat outward radial field. Conversely, if they are moving towards the south pole of a magnet, they are traveling towards a somewhat inward radial field.
Thirdly, we need to know our Fleming’s Left Hand Rule.
So, if the north pole of a magnet is pressed into the CRT screen, the electrons coming towards the north pole should be deflected in a clockwise direction (use Fleming’s Left Hand Rule). This was the situation at 00:36 of the video.
On the other hand, if the south pole of a magnet is pressed into the CRT screen, the electrons should be deflected in an anti-clockwise direction (use Fleming’s Left Hand Rule). This situation occurred at 00:24 and 00:48 of the video.