Amanda Bynes danced furiously in a New York clothing store before trying to pilfer a shirt ... and TMZ has the video.

If it were anyone else, it would be both fun and funny ... but in Amanda's case it's desperate. You see her inside Pookie & Sebastian browsing the racks before busting into some wild dance moves.

Amanda's burly driver got way more than he bargained for as Bynes did a full body search in the middle of the store.

TMZ broke the story ... Amanda tried a sticky finger move on a shirt Wednesday before a store clerk confronted her. A short time later, she was nabbed by security at Barneys for allegedly trying to steal a hat.

No one filed charges.

Amanda's life both in danger and limbo ... we know her parents have not decided whether to go back to court and ask for another conservatorship. Absent that, the only thing authorities can do is place her on a psychiatric hold, but ONLY if she poses a serious danger to herself or others.