The factors of fair use are:
the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
the nature of the copyrighted work;
the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
the effect of the use upon the potential market for or value of the copyrighted work.
15 minutes summary seems to contradict most of those four factors. At least:
- 15 minutes is a lot compared to a 1-2 hours long movie.
- Since viewing a 15 minutes summary could be a substitute for viewing the movie, distributing it has a large effect upon the potential market value of the movie.
- You don't seem to be making an educative work, just a shorter version of the same film for its entertainment value.
IANAL, but it seems unlikely that you could claim fair use for such a summary.
Additionally, at the end of the question body you ask a different question, about whether the summary would be considered transformative enough to be original. The answer is that no amount of transformation alone makes a derivative work original (that is, non derivativa), and even less when the original work is essential for the derivative work, like in your summary.
That is quite unrelated to whether your usage of the movie parts fall under fair use, although transformation may help comply with fair use factors: the less from the original works that remain after transformation, the less portion you are actually using from it, and the less the market value of the underlying work is reduced.