as complicated as it seemed to be for me, it took me almost 2 months of "trying" things, thinking it was my bluetooth, etc. i feel your frustration. i hope this helps.
after you create your ringtone, save it to your desktop, don't choose to transfer it via bluetooth just yet.
after you save it to your desktop, single click on it, you have to rename it.
whatever you named it leave that alone, there will be a dot and a number, letter after it, probably 3ggp, or something like that. if you rename that to 3g2 it should work. it may say "file may become unusable" or something like that, ignore it and save.
then when you go to your bluetooth, with your phone already paired and connected, go to file transfer, a box will come up with everything you have transfered there. just single click on the ringtone you saved on the desktop, and drag and drop to the "bluetooth shared file" you just opened. it should transfer to your phone. i kept getting the same "invalid file type" message, and finally figured out it was as simple as making sure the name ended in 3g2
hope this helps (also you know these have to be video ringtones?) ventones is the best.
ps - i always transfer using bluetooth, and don't have a card or whatever that is