Question
Where is this vid you speak of?
(link plez)

my two sense

IF your objective is to be able to play Grateful Dead songs specifically

THEN I'd pick a Grateful Dead song

AND reverse engineer my studies in that context.

everything on the site will apply to any application that's how music works.

any scale lesson
just transpose to the key applicable to the song you want to learn

any chord lesson... that's finger dexterity coordination; and those chords will come up in some Grateful Dead song eventually

the key to learning ACTIVELY processing the information
"How does this apply to my objectives?
How is this universally applicable?

etc

it's all hands on the guitar it's all universal knowledge of the instrument

and as long as your engaging with your primary goal in mind 
long term: GD songs
short term: THIS particular GD song...

THEN you'll streamline your progress; and enjoy the process.