If the PLAY VIDEO selector doesn't start it, select the right arrow icon on the bottom near the slider.
In case you missed it, the 8 track assignments were:
1 - lead vocal
2 - group vocal
3 - tambourine/conga
4 - organ/piano
5 - guitars
6 - horns
7 - drums
8 - bass
In our current world of almost unlimited tracks working on only 8 might be tough to comprehend, but it was the way it was done in those days (and successfully so) when that was all that was available. It remains a tribute to the people involved that so much could be done with so little, from the musicians to the arrangers to the producers to the engineers. Of course, with all that great talent, the technicality of something like number of tracks becomes a small factor in their success.
If you're an artist or engineer, try limiting yourself to just 8 tracks on a project. It might bring out some additional creativity you didn't know was there.