Hi @Leonardo1189
I also want to send a standard arrival PDF via the Airbnb messaging system, but one cannot upload documents, only photos. Fortunately mine is only one page, so I have turned it into a screenshot and I send it as a photo on Airbnb.
If your PDF is not too many pages, you can also do this, but it won't solve the problem with the video that you want to send.
One solution would be to send both as attachments in a WhatsApp, but Airbnb wants you to keep communication inside the app. Once you send a WhatsApp, the guest is likely to keep communicating there instead of on Airbnb. This is risky as it violates policy and you will be unable to present credible evidence to customer support or to the safety team if anything goes wrong.
I'll follow this thread to see if other hosts have good ideas!