I haven’t seen this answered anywhere on the internet and I just had this exact same problem, or mistake I should say, so I thought I would add to this old thread with a concrete answer. Having spent the last hour or two trying to figure this out, I have the solution.
You no longer need to export an image sequence from Final Cut Pro and then import said sequence into photoshop as layers. This is the old way.
1. Export a Quicktime file from Final Cut Pro, etc.
2. Go File>Open in Photoshop.
3. Edit Away and then when you are done, go to File>Export>Render Movie
…
If you’re stuck like the poor schmuck above and did it the old way (and really don’t feel like doing it again), don’t fret – it’s normal for you to have an exported video of only one frame, it’s because you’ve gone about it the wrong way.
Go to File>Scripts>Export Layers to Files … this will spit out a new Image Sequence which you can load into FCP (or whatever you’re using).