The video is 21:55 in duration. It has a stereo audio track. the right channel has data transmission sounds and the left channel has what appears to be a distorted/warbled version of the right channel. The audio also contains shifting amounts of DC offset.
In the right channel, several series of numbers are spoken. At about 1:44: “8999”, and about 16:35: “4999”. (There are possibly more.)
However, at around 10:30 it seems that “0” is spoken in the left channel, followed by “2999” in the right.
At around 1:11 to 1:33 there is morse-code-like sounds. Isolated audio
Discord user its a-me markio has noted that some of the “keyholes”/dots have a trailing effect. (These may also appear in other videos — further research is required.)
Alternate width of 789.5:
BRILL 49999 is part of the BRILL Composite group.