They had the rules in text below the video:
VENKMAN RULES (As seen in this video.) Venkman is played out of a single deck. The first draw on each player's turn is replaced by a draft. Any other draw is normal - off the top of the deck. The deck is placed on one side of the play area, a clue token is placed on the other. Starting Hands - From the five basic lands, each player is dealt two random lands. The fifth is put in the deck in a random place (If one is being very fair and shuffling it in, it's quickest to do it when shuffling between games.) Players then take turns drafting. The player on the draw drafts first. After that player has drafted their fourth time, the other player begins their first turn. Drafting - There are two options in the draft. The first option is to look at the top three cards of the deck, put one into hand, remove one from the game, and add the third to the farthest side of the offer line (initially, the clue token is the offer line). The second option is to take half of the offer line, rounded down, that is closest to you. If a player takes the clue token from the offer line, it is then on the battlefield, under that player's control. There is a normal hand size of seven and it is first checked at the end of each player's first turn. Each draft is considered a single card draw, no matter which option was chosen or how many cards were put into hand. The game is paused during drafting. If the top card of the library would be revealed, it is not revealed until the draft ends. If a player would search the library, that player has a choice. They can search from among the top ten cards of the library, bottoming the rest, or they can search from a group of set aside cards (basic lands). Scry X works differently. A player has a choice when scrying. They can use it the normal way, or they can replace the closest X cards in the offer line with face-down cards from the top of the deck. If any of those cards in the offer line were face-down, that player may look at the face-down card(s) first before deciding whether or not to replace it(them). If a player would draw a card from the library but cannot, the player with the most life wins. If the players have the same amount of life, everyone wins.