Dave, here is the link MLB sent me.
https://www.mlb.com/login?redirectUri=https://commerce.mlb.com/purchase?mlbSku%3D1001107599999910221901000%26offerCode%3DAR437XY2428D%26campaign%3D%26flow%3DPURCHASE%26partnerId%3Ded-13649166-1137679383&campaignCode=mlbtv&partnerId=ed-13649166-1137679383
It took me to an MLB.TV sign-in. Used the same ID and password as my regular MLB website sign-in. Hope it works.
https://www.mlb.com/login?redirectUri=https://commerce.mlb.com/purchase?mlbSku%3D1001107599999910221901000%26offerCode%3DAR437XY2428D%26campaign%3D%26flow%3DPURCHASE%26partnerId%3Ded-13649166-1137679383&campaignCode=mlbtv&partnerId=ed-13649166-1137679383
It took me to an MLB.TV sign-in. Used the same ID and password as my regular MLB website sign-in. Hope it works.