There’s no doubt that the May 1st release of Marvel’s latest film, Avengers: Age of Ultron, will be a huge box office draw. Last year’s trailer debut already drew a massive online audience, and Marvel recently debuted a new ad that ran during the college football playoff championship earlier this week.

But the real sparks flew when Marvel posted the trailer online to both Facebook and YouTube, at the same time. Many companies were paying close attention to the numbers generated by the trailer, to get an idea of how they would shape up in competition with one another, according to Adweek.

As you might guess, the trailer did big numbers with its arrival. Within its first 24 hours, it was viewed more than 12 million times across both sites, providing proof that Facebook could be just as effective as YouTube when it came to promotional advertising.

In an interesting move, Marvel’s championship game commercial was first directed towards its Facebook page, rather than YouTube. “It’s very easy on Facebook to virally spread an ad, users click one button and share, whereas on YouTube it’s a little more clunky and not as easy as one click,” said Debra Aho Williamson, an analyst with eMarketer. “So, a lot of marketers are considering the power of Facebook to share video quickly and easily.”

That’s not to say YouTube will lose business anytime soon, as many businesses and marketers still consider it a go-to partner. However, Facebook is clearly on the rise, with users viewing three billion clips on a daily basis, up from the one billion just a few months’ prior.

eMarketer’s numbers show, however, that YouTube continues to lead the pack, with 162.3 million viewers in October, compared to Facebook’s 93.8 million viewers. But could this change soon

“Facebook is a challenge, but marketers and agencies are very used to using YouTube as a library of content to point people to videos,” said Williamson. “They don’t want to create baby YouTubes on every social site.”

That isn’t stopping companies from looking, though. “It’s great that Avengers got roughly the same number of views,” he explained. “But what is the sharing that is happening in one versus the other ”

It’ll be interesting to see where the video advertising game goes from here…but don’t think this is over for Avengers. There’s still three and a half good months of advertising before it launches in time for the summer movie season.