I have some videos uploaded to Youtube but only a few of them that Youtube has automatically generated the subtitles for. However, all of videos are spoken in native American English. Yes I admit that some are of quality less than perfect. I seriously hope Youtube will generate the subtitles for me. How can I make it? Or how can I enhance or modify the video so that Youtube will recognize its voice?

I'm not too lazy to create subtitles on my own. I actually want to know what they say because I'm able to read English but not listen to it very well (I'm not English-native)