No, you can not.
You can move them to Cloud 1 without any issue and they will be removed from your server. But if you try to change to Cloud 2 you could break the URLs of the ones stored in Cloud 1.
Storage is as cheap as it gets now a day. You can get ~250GB for 5$ and those last a really really long mile. Using free services is not free and will cost you a lot on consistency and availability of the multimedia in the long term.
One of the things I love of Discourse is that all the media is stored locally, my site manages how-tos and community related photos. All the posts pre-Discourse are broken and most of them are never recoverable because of free storage options.