This is the trailer shown at the end of the most recent Nintendo Direct. It shows off and reveals the new characters Charizard and Geninja for Super Smash Brothers. Super Smash Brothers for 3DS will be released Summer 2014. The Wii U version will be released shortly after in Winter of 2014.
The video itself is in Japanese, but you can probably suss it out. More detailed information and screenshots can be found here.