video – Need help accessing the key when trying to decrypt .ts files via ffmpeg

I have downloaded all the individual .ts files and the corresponding m3u8 file from a VOD and I now want to merge them together into a single watchable file.
The problem is, that the .ts files are encrypted and don’t understand how to access the key.

Here’s the beginning of the m3u8 file:

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-TARGETDURATION:4
#EXT-X-PLAYLIST-TYPE:EVENT
#EXT-X-MEDIA-SEQUENCE:6484
#EXT-X-KEY:METHOD=AES-128,URI="irvine://aes",KEYFORMATVERSIONS="1",IV=0x1E9ABA2B3C916D47D592D9B1E7674F4B
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:24:59.682Z
#EXTINF:4.004,
index_1_6484.ts
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:25:03.686Z
#EXTINF:4.004,
index_1_6485.ts
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:25:07.690Z
#EXTINF:4.004,
index_1_6486.ts
#EXT-X-PROGRAM-DATE-TIME:2024-05-25T07:25:11.694Z
#EXTINF:4.004,
index_1_6487.ts
...

As far as I understood I only have the initialization vector and I need to access the URI to get the actual key.

I have tried to decrypt the playlist with the following command:

ffmpeg -i index_1.m3u8 -c copy output.ts

But I would always get the following errors:

Unable to open key file irvine://aes
Error when loading first segment 'index_1_6484.ts'
Error opening input: Invalid data found when processing input
Error opening input file index_1.m3u8.
Error opening input files: Invalid data found when processing input

I have also tried just decrypting a single .ts file to start with, with similar results.

ffmpeg -decryption_key 1E9ABA2B3C916D47D592D9B1E7674F4B -i index_1_6484.ts -codec copy index_1_6484_out.ts