BTW looking at the example solar spectrum in the video, the resolution is nowhere near 2nm (more like 5-10x that). Compare with my simple “SEPSA” (Slit-EyePiece-Star Analyser) setup for example
http://www.threehillsobservatory.co.uk/astro/spectroscopy_18.htm
or the slitless collimated Junk Box design
http://www.threehillsobservatory.co.uk/astro/spectroscopy_19.htm
These are just a bit of fun though. A slit/fibre fed spectrograph really needs a guider module so you can find, focus and place the star on the slit/fibre and keep it there
Cheers
Robin