Convert MT2S to FLV

Converting .mt2s files directly to Flash Video Files (.mt2s to .flv conversion) is not possible, since .mt2s is a non-existing format.

Perhaps this is just a typo, and you are actually searching for ways how to convert Blu-ray BDAV Video Files to Flash Video Files. In that case, please refer to the .m2ts to .flv conversion entry.

Simply put, it is impossible to convert MT2S to FLV directly.
Thus, there is no so-called mt2s to flv converter or a free online .mt2s to .flv converter to be found.