Yes, PLAYBACK is a Scrabble word!

Letter values in Scrabble US: P 3, L 1, A 1, Y 4, B 3, A 1, C 3, K 5.

Is it a valid word?

PLAYBACK is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the act of reproducing recorded sound
electronic equipment comprising the part of a tape recorder that reproduces the recorded material