Invalid File-Type - expecting HL2DEMO

[shark25361]

I'm trying to parse the .dems from https://www.hltv.org/matches/2350388/vitality-vs-natus-vincere-esl-pro-league-season-14 using a build from DemoInfo with signed assemblies disabled. However, the following code:
DemoParser parser = new DemoParser(File.OpenRead(args[0]));
parser.ParseHeader();
causes the following error:
Unhandled Exception: System.IO.InvalidDataException: Invalid File-Type - expecting HL2DEMO
at DemoInfo.DemoParser.ParseHeader()
at csgo_highlights.Program.getKills(DemoParser parser)
at csgo_highlights.Program.Main(String[] args)

[moritzuehling]

Did you unzip/unrar the file from hltv.org?