From Bitdefender Support today:
Dear XXXX,
Thank you for your interest in our security solution, Bitdefender, and for having contacted us.
We apologize for the delay of our response and we assure you that we will answer in a timely fashion from now on. 
We kindly inform you that Bitdefender is not compatible yet with Windows 10 ,because it is still in Beta testing therefore Bitdefender is not yet optimized for it.
and when we will have a product that will be compatible with Windows 10 you will see it on our website.
XXXX, please let me know if I could offer you further information.
Have a nice day!
Best regards,
Marius Dogarescu
Bitdefender Support Team
In all seriusness I think the e-mail from Bitdefender support, confirms there will not be a Beta as such but just an update that will require a restart. Christian will probably note it in his update post. However rest assured if you are not sure when Bitdefender is supporting W10 you can always go to their website and read the website looking for Windows 10.
You have to read the website to know what's in it
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