Yes, HYBRIDIZING is a Scrabble word!

Letter values in Scrabble US: H 4, Y 4, B 3, R 1, I 1, D 2, I 1, Z 10, I 1, N 1, G 2.

Is it a valid word?

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

(genetics) the act of mixing different species or varieties of animals or plants and thus to produce hybrids

Not playable in Scrabble US: HYBRIDISATION, HYBRIDISE.