If you have an older version of FTM (FTM2014 and earlier) then RootsMagic Essentials (free) will allow you to download the tree to your computer including media. That can be exported as a Gedcom with links to media and then imported by FTM as a new tree.
If you save your existing FTM tree as a full backup including media then RootsMagic Essentials can import that file and then upload it to Ancestry as a tree with media that you can work on. Later you can bring it back to FTM via RootsMagic. I did this during the recent 1939 free trial and it worked okay.
If you save your existing FTM tree as a full backup including media then RootsMagic Essentials can import that file and then upload it to Ancestry as a tree with media that you can work on. Later you can bring it back to FTM via RootsMagic. I did this during the recent 1939 free trial and it worked okay.