Q: Is it possible to link an external USB to transfer video files?

It is kind of possible. There is the camera connection kit.

needs to be in DCIM folder.

proper name of eight characters plus extension

flash drive doesn't draw too much power or have to use powered hub.

will be copied to ipad.

proper format -- .avi, .m4v, .mp4, and .mov  -- http://www.apple.com/ipad/specs/

http://blog.manetyim.com/2012/05/import-any-picture-to-ipad-with-connection-kit/

http://support.apple.com/kb/HT4101

Airplay will be coming with ios 7.

There are combination usb and wifi flash drives.

Airstash

This dual personality device is both a WebDav device which allows you to transfer files via Wifii between device & iPad and a thumb drive which works with compuers.

Compatibility

Wireless operation:

    Web browser WiFi b/g capable device

    Optimized experience for iPhone, iPod touch, and iPad via HTML5

    No internet connection required

USB operation:

    Compatible with most operating systems that support USB Mass Storage Class (thumb drives)

    Firmware update via file drag and drop

http://www.airstash.com/

rccharles wrote:

 

Airplay will be coming with ios 7.

 

I presume you mean AirDrop, yes? That will work only between iOS devices, not between an iOS device and a Mac, at least as of the information released by Apple thus far.

Regards.