Seeding?

It says 100%, but it says seeding. Can I close it and play, or do I have to wait for something? I've heard other people quit seeding and it's not necessary.

 

You can quit seeding if you want.

 

As this is a torrent based updater everyone downloads the update from multiple seeders rather than just 1 server, although BeamNG have 5 servers seeding too. When your updater says seeding, you have become a seeder and other people will begin obtaining the update from you partially.

Generally in torrenting circles it is considered courteous to upload as much as you download. Of course most people don't do that.

Regarding BeamNG. Once it hits the seeding stage you can run the game fine (dont need to close updater first). Whether you close it or not is upto you. But considering the low download speeds people have been experiencing it would be appreciated by others if people seeded a little more.
I have a very poor internet connection but so far have managed to seed 80mb and 150mb in 2 seperate chunks.