From Jonathan Handel's blog:
The issue is which union has jurisdiction over original programming made for new media. The AFTRA deal, which was ratified four months ago, has a provision that says “[i]t is understood and agreed that AFTRA shares jurisdiction” over such programs. That provision would seem to give producers a choice of unions when making such shows.
However, when reviewing the AMPTP offer to SAG, I noticed that the comparable language—“[i]t is understood and agreed that SAG shares jurisdiction”—is struck out...Instead, there are a footnote and another paragraph which state that the studios and SAG disagree on whether jurisdiction would be shared. The language then states that each party reserves its legal positions on the issue. In other words, SAG refuses to agree to shared jurisdiction, and the AMPTP is not pressing the point.