YouTube mkaes it more easy to with subtitles (speech to text)  in videos. The feature is still in trial phase and only works on videos in English, but subtitles are available in various languages. so while you are watching video from different language there is potential for subtitles, there is an extra menu in the bottom right corner where you can turn it on and off and select the language to be translated into.
The system is not perfect, since there may be errors in speech recognition, and additional errors if one chooses to translate into another language. However, it is possible to suggest corrections to the generated text. Another option is to use a feature they call “Automatic Timing”. To use this feature, you must upload the video with a text file with everything that is said in the video, YouTube will automatically attempt to find out when it is stated in the file that is said.
Beyond that could provide subtitles for those who have difficulty in English, so it is expected that especially the deaf will enjoy the feature.
