how to contact linus or someone else at LMG
"I'm sorry what?" was my first reaction to this. I'll lock this to prevent community tearing you to shreds.
Firs of all, all LMG employees have accounts on the forums. You can try to reach them out this way, but unless its important issue with Floatplane, LTTStore.com, one of the sponsors, fake channel or something along those lines, they most likely will ignore it.
As said, LMG has lots of social media accounts. You can find them listed in here https://linustechtips.com/main/topic/34488-follow-linus-media-group/ or at their official website https://linusmediagroup.com/. Website has also Contact Us form to make more official, like business, inquiries. Even their Youtube channel has contact info for business inquiries https://www.youtube.com/user/LinusTechTips/about.
As last note. Your opening post is very messy, and sorry to say this, makes you look very unprofessional and rather young. If your intention would be to make video building PC with Linus as a fan, that probably won't happen. LTX is much better place to meet him. Linus is company CEO and very busy man. So only way overall to get to make video with him is to have notable Youtube channel where you both can benefit from it, or represent some company which is willing to shove money to him, or get chosen by another company or foundation (ROG Rig Reboot or Make-a-Wish etc.). Contacting someone for business proposal (pretty much what making video with Linus/LMG is) should be treated like applying for a job. Using proper language and presenting reasons why this should happen. How will they benefit from it etc.