Does the Eternal Calm have anything to do with the storyline of ffx-2?

Yeah, it's a connector that was released on X International that showed Yuna talking with Yaibal and then joining the Gullwings after she's shown the New Beginnings Sphere. If you've already played both games, you're not really missing anything.

Ive only played ffx. So the eternal calm video isnt on ffx 2? Is it important to watch if i want 2 play ffx 2? Is the video Eternal Calm part of the ffx 2 stroyline?

Like I said, it's a connector. If you've played FFX, you really have all you need. Everything then in FFX-2 is really self-explanatory. The Eternal Calm video just gives backstory if you absolutely must have it. Try a Google search for "Eternal Calm" if you want it.