This Animation was done in flash and you can view a higher quality version here:
http://bidujador.deviantart.com/art/Vocaloid-Lovers-Valentine-111807744
It is is my entry for the Vocaloid Lovers club's Valentines contest here:
http://vocaloid-lovers.deviantart.com/journal/22472001/
It took a while to finish it because everything you see here was made by me including the voices using the vocaloid 2 software. I couldn't figure out what to do, then it struck me I just had to make vocaloids do what they do best: sing. It was fun to draw them too ^__^
If you love vocaloids or would just like to support me please join and vote for me.
http://vocaloid-lovers.deviantart.com/

Vocaloids featured:
Hatsune Miku - Soloist
Kagamine Rin & Len - Backup
Yowane Haku - Just wanted to be in the movie, so she managed to sneak into it somehow XD

Disclaimer:
I still hate Valentine's with all my heart and do not celebrate it, but I'm doing this because I needed to practice both flash animation and the vocaloid software... and because I LURVE Hatsune Miku ^__^

Vocaloids © Yamaha/Crypton
"I will always love you" © Dolly Parton/Whitney Houston