For anyone trying to get a direct service from Brasov to Bucharest otopeni airport or vice versa here is how I managed to do it.
All the info I could find online about getting from Brasov to Bucharest airport involved going in to Bucharest city then back out to the airport. This seemed like a lot of hassle so I asked around and found a direct service from Brasov to Bucharest otopeni in an air conditioned minibus for pretty much the same price as going the long way.
The direct service leaves every couple of hours and can be found here Direct service between Bucharest airport & Brasov. I purchased my ticket from the hotel where the bus departs in Brasov, there is a travel agent inside the hotel. You can also book it on the website above. It cost me about €15 for a single journey. Bon voyage 🙂