The studios claimed the talks were being held up by a demand to double fees paid to actors for DVD sales - a move producers said would raise costs $500 million over three years.
SAG lowered its push to what would effectively be a 15 percent increase in those fees, said the people, who were not authorized to comment publicly and requested anonymity.
The revised proposal calls for the increase to come in the form of health care and pension contributions by producers to the union, one of the people said.
The guild also reduced its demand for a 50 percent pay increase for guest stars on TV shows, both people said.
Friday's developments represented a "hopeful sign" that a deal would be reached before the three-year contract covering theatrical movies and primetime TV shows expires June 30, said entertainment lawyer Jonathan Handel.
The two sides are negotiating a multiyear contract, the length of which was still being hammered out.
"The question is, will negotiators succeed in closing a deal, or will they run out of runway?" Handel said.
One of the people said that despite the concessions, the sides had not agreed on a range of issues, including the revised DVD and guest star proposals.
In a joint announcement Friday, the guild and studios said they had agreed to a second extension of talks through Tuesday, with one day off Sunday. The negotiations had been set to end temporarily on Friday after lasting 15 days.
The smaller American Federation of Television and Radio Artists had set its talks for Monday but said it reset them for Wednesday to give the sides more opportunity to succeed.
SAG and the Alliance of Motion Picture and Television Producers have said they want to avoid a repeat of the 100-day strike by Hollywood writers that shut down production of dozens of TV shows.
The guild has said it would push for a better deal than writers and directors received in previous negotiations with studios, specifically over residual payments for DVDs and content distributed online.
That goal could prove difficult because actors, writers, directors and technicians have long accepted residual shares based on the proportion of workers from each group on a given show.
It was not clear if writer or directors would immediately seek the same terms if actors received a sweeter deal.
If it fails to secure better payments involving DVDs or Internet content, the actors guild could be forced to call for an unpopular strike or seek concessions from the studios on other issues, said Norman Samnick, an entertainment lawyer who represented Warner Bros. in previous contract talks with actors and other unions in Hollywood.
"It's going to take six weeks to figure out what kind of fig leaf they can get," Samnick said.
The guild has stood by its earlier claims that actors were struggling economically.
In its Wednesday statement, the studio alliance said the DVD market was flat and it wasn't the right time to add significant new costs. The studios also rebutted the guild's claim that actors' pay is declining.
Actors' pay for theatrical-release movies rose 6 percent in 2007 from a year earlier to $596 million, and increased 1 percent to $705 million for television appearances, according to alliance estimates.
AFTRA was expected to reach a quick deal with the studios for a handful of primetime shows, including "Curb Your Enthusiasm."
Earlier this week, it said 93 percent of its members who voted had ratified a separate contract covering TV shows such as "Oprah" and "Entertainment Tonight."
Most performers will receive a 3.5 percent pay increase retroactive to last November. New provisions were also set up for Internet content modeled on deals accepted by writers and directors earlier this year.
