Analyze the video. Then have a list of options that allow you to either directly hardcode the text into the video via muxing or create an external subtitle file in formats like srt, smi etc which would allow for the subtitles to manually be loaded into video players.
Another amazing feature would be to translate that to another language as well directly into the video or to create an external sub file.
Program looks to have promise however the only real issue is in regards to the pricing structure. Far better to have a combination of payment options. 1) A one off payment to directly own the program so that they can do it on their own time. 2) Online option per video for someone who may only need a small amount of work done. 3) Monthly option for power users that have a lot of videos to be processed.