I’ve worked with a Remax affiliate. (Not the big Remax but someone entitled to use the Remax logo). I’ve also recently worked on sales copy pieces promoting Sage for a national Sage software vendor, as well as Malta’s leading fast-food delivery company. - That last one wasn’t on Fiverr though.
In either case, if you are looking for people with links to big brands that you can promote to say how amazing Fiverr is, you might have a hard time. With my Sage and Remax work, all that came through resellers. i.e People already outsourcing their own clients work to Fiverr. The Remax and Sage people I worked for won’t, therefore, know that their work got done via Fiverr and I’m guessing that if they ever found out there could be problems.
In short, Fiverr is supposed to be a secret. The fewer people who know about it, the better the world is for resellers who bring in the most business.
That said, I did just do a property sales video for a new housing development in Austin, in this case, maybe you could/should focus your marketing outreach onto mid-big sized upcoming brands, the kind who find Fiverr organically by themselves and use it as their own secret weapon for grass roots business success.
Besides, big brands want people to think they have just spent gazillions on their latest sales copy and the like because being big is part of their brand identity. Upcoming brands, on the other hand, would jump at the chance to get any kind of cross promotion.