XF 2.2 How can I do attached and show content or multimedia on the forum from a subdomain

[albertc.s]

Well, I'm having trouble serving attached content, especially videos from my main domain and I've thought of creating a subdomain for example "videos.mydomain.com"
What can I do or what rule could I use so that users who upload video are saved in the subdomain and displayed from the subdomain?
some idea?
thanks in advance!