what video problem will be introduced when frame rate is dropped?

Again, don’t try dropping the frame rate from 29.97 to 15, because you can introduce more problems than you solve.

( what video problem will be introduced when frame rate is dropped? )

When FPS drops below 30fps, the human eye can start to detect that the 3D image starts to appear jerky and "laggy"

time and control codes

timecode is physically recorded with the programme, its relationship to that programme is fixed, and can be used as an accurate reference.

The Secret to Encoding High Quality Web Video: Tutorial

The Secret to Encoding High Quality Web Video: Tutorial

• many factors that contribute to video quality
• data rate / frame rate / bits per pixel value / resolution
• the more motion in the video, the higher the bits-per-pixel value needs to be to produce acceptable quality video.
• the .091 for low motion and .175 for high motion are good rules of thumb at SD resolutions
• Ben Waggoner - the power of .75 rule
• author's book - Video Compression for Flash, Apple Devices and HTML5