It's a HP 9825B desktop calculator and a HP 9872 flatbed plotter.
By the looks it can be eitehr a HP 9825 desktop calculator (*1) introduced in 1976, or a 1978 HP9831 computer (*2).
(HP 9825A Picture taken from Museum of HP Calcultors)
(HP 9831B Picture taken from HPmuseum.net)
The fact that the video shows a calculator style keyboard does not help to distinguish between 9825 and 9831 as both were available with either full travel (xxxxA) or calculator style (xxxxB) keyboard.
But the 9831 was only available for a very short time in 1978, while the 9825 was produced and sold from 1976 until 1983. Thus, going by the recording year of 1977, this can only be a 9825B.
In turn the plotter seems to be a HP 9872, introduced in 1977:
(HP 9872 Picture taken from HPmuseum.net)
Looks like he got him the newest HP tech of 1977 in 1977 :)
For more information see HP 9825 entries at
For the HP 9872 Plotter see
*1 - While HP classified the 9825 as top end calculators and follow up of the 9820, its handling is way more like a later personal computer, including a language called HPL, somewhere between the key-press recording of calculators and BASIC, which the 1972 9830 used.
*2 - The 9831 is essentially an 9825 with a BASIC/OS compatible to the 9830. This is possible due the whole 98xx series using the same base CPU derived from the HP 2100 CPU line.