Yes it used to be 1000 now it's 5000. Reason being channels with 1000 subs usually did not have the interaction rates that companies were looking for. But honestly 5000 subs is low. But some channels with 5000 subs do get very high interaction rates and they can get deals.
I have a cooking channel and they do not have a lot of deals that fit what I do.
The way it works is you find a campaign you're interested in and apply. You make a pitch to the company of what you will do, how much you will charge and your deadline. Your pitch needs to be professional or you will not get the deal. The company will review your pitch and approve it or move on. Most do not reject your pitch. If approved the money is placed into escrow. The company will now send you the product.
After you receive the product you review it. If you do not like it contact them and tell them you do not like it and offer to send it back. (I always look up reviews online before applying. I also make comments in my pitch showing that I know what what the product is). If you like it then you make the video and usually upload an unlisted one for the company to review. In case you got the name wrong etc. Then you release the video and get paid.
All communications and steps should be handled on the Fambit website. If you do what your approved pitch said then you will get paid.
Beauty and fashion are the biggest target audiences that I see (I see lots of campaigns for push up bras). I have been signed up from the start and just now doing my third campaign. But most of the time I am to busy to commit so I will go a month or two without even logging in the the website.