Dear Mister/Madame,
I think I am the right person for this task. I have experience with mobile application translation and I am currently studying for my Master's degree in an international environment in Linz, Austria.
For this kind of project, I usually go for an incremental workflow in order to be able to translate, check, review and adjust.
For 15 min video, it usually takes me 4 hours as I tend to check my work again and again.
Therefore I will deliver your translated subtitles in about two days in order to be able to do a great job.
Sincerely,