You earn pronunciation points each time you record lines in a video. When you come back later to the same video, your previous session will be reloaded and you can improve your score. Points from different modes and videos are added up to your total. The amount of points you get depends on the video's difficulty level, the line length, and how well you spoke the line.
In general, the EnglishCentral system deducts points each time it believes you may have made a pronunciation error. Dropping words altogether results in the most significant penalties.
The easiest videos are worth a few hundred points each and the most difficult ones can be worth several thousand points. Each video has a difficulty level and point value based on the sentence length and word complexity of the video.
Videos may be re-recorded as many times as you like, but only your most recent score is counted.