A possible concise summary is:
The speaker is a game theorist who tries to prove that Sans from Undertale is actually Ness from Earthbound, a game he loves. He uses evidence from both games, such as items, maps, dialogue, and character design, to support his claim. He also mentions a Halloween hack of Earthbound made by Toby Fox, the creator of Undertale, that connects the two stories. He invites the viewers to watch his other videos on Undertale and Earthbound, and to join him on a live stream of the Halloween hack.
Here are some possible facts extracted from the text:
1. Sans is a skeleton named after the font Comic Sans.
2. Sans has a brother named Papyrus, who is also a skeleton and named after a font.
3. Sans has knowledge and power over space and time, and can remember the timelines of the player.
4. Sans has a hidden workshop with a photo album, a badge, blueprints, and a broken machine.
5. Sans wants to go home and go back, but he has given up on both.
6. The badge in Sans's workshop might be the Franklin badge from the game Earthbound.
7. The photo album might be related to the one in Earthbound that shows the journey of the characters.
8. The broken machine might be the Phase Distorter, a time machine from Earthbound.
9. Sans might be Ness, the protagonist of Earthbound, who got stuck in Undertale's world and became a skeleton.
10. Undertale might be connected to Earthbound in its setting, characters, and themes.