In my opinion, Eight people is a lot to run even for experienced DMs. It is not impossible, but it can be difficult and slow, especially if you are not used to it. That is not say you shouldn't try. . . but just to be aware. I honestly would recommend breaking the group up into two groups of four and running separately for each.
But even if you do have that huge a group, if everyone is newbies, consider running the first session or so's encounters with the number and kinds of opponents as written. It may turn out to be "too easy" but it will let the players warm up and get used to what their characters can do. Later you can pump up the HPs of solo monsters to 3/4s of max or max and/or add 1 to 2 opponents per PC above 5 for groups of lower CR creatures. Just be aware that adding on additional opponents can be more deadly for some kinds of monsters than others. It is easier to slowly ramp up to get a feel than to go overboard from the beginning and try to reel it back.
I don't have a video to recommend, but hopefully someone else will pop in to help with that.
Oh, and welcome to the boards.