"DDP2" refers to Dolby Digital Plus (E-AC-3) with 2.0 channels . This is efficient for streaming and supports better dynamic range than standard AC-3, even in stereo.
The this filename indicates is that it uses HEVC (also known as H.265) compression at 720p resolution . Download From S03E04 720p HEVC WEB DDP2 264 HDKing mkv
Here is why that is a valuable feature:
Based on the filename you provided: