Capture and convert Streams from Vlive.tv - Problem to decrypt

[sanduhrgucker]

Hi,
My Daughter bought a celeb-interview on Vlive.tv
After the payment she feld sad because she read the videos can only be shown at the mobile app.
So she asked me to fix that. I failed at the last step... please help!

here is what i did:
1.) i downloaded the film in the Vlive app
- to to this, i had to rename some supersu files because the app recognised corectly my mobile is rooted.
2.) i transfered the file (a zip-file) to my pc then i unpacked all the stuff
Inside are:
- a Key file
- a m3u8 file
- thousands of .ts files

The content inside the keyfile seems to be binary.
The m3u8-file begins with:

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-TARGETDURATION:7
#EXT-X-KEY:METHOD=AES-128,URI="a32c23U4Tlo5Utw5NUg_srUcSQ_rmcvideo_1080P_1920_5120_192.key"
#EXTINF:5.805811,
a32c23U4Tlo5Utw5NUg_srUcSQ_rmcvideo_1080P_1920_5120_192-000000.ts
#EXTINF:5.372033,
a32c23U4Tlo5Utw5NUg_srUcSQ_rmcvideo_1080P_1920_5120_192-000001.ts
#EXTINF:5.205200,
a32c23U4Tlo5Utw5NUg_srUcSQ_rmcvideo_1080P_1920_5120_192-000002.ts
...

I think it should be possible to decrypt because i have the right key. But how? ;-)

Any Hint is welcome!

Regards
Rene'