Video requires a constant frame rate. Clips without that are "out of spec" and may well not work.
Let me clarify just a bit - it's not that there's frame rate variability within a single clip; it's just that the camera doesn't use the same frame rate for each video it records. PP seems to recognize the frame rate fine when I import the clip (can inspect clip properties and the numbers are right) but the sync just isn't preserved.
It's quite possible the camera is varying the frame rate within the clip, and that's causing sync to go out. PP can only report one number, it doesn't recognize variable, so that's not an accurate gauge here.
Ah. I'll ask the Dropcam folks the particulars on the camera's frame rate stability.
Jim - you were spot-on. Here's the response from Dropcam, in case anyone else had the same issue:
You are actually correct in that the frame rate for Dropcam's video does vary depending on a few factors. The fps slows down for night vision to average out image noise and increase the image quality. The fps will also slow down when there is no motion going on in a scene to conserve bandwidth.