Valve itself "leaked" the 2009 Left 4 Dead 2 trailer.
Brief · Source report
Valve staged its own Left 4 Dead 2 trailer "leak" to get around an ESRB ban, says former writer
Source excerpt. Read the original for the full report.
Brief · Source report
Source excerpt. Read the original for the full report.
Valve itself "leaked" the 2009 Left 4 Dead 2 trailer.