In the context of acoustics, "ts" almost always means time-step (inverse of frequency). But I don't have the faintest idea of how it would collide with the username string :|
In the context of video streaming, ts probably stands for "Transport Stream" [1] and nothrabannosir's idea of the bug is probably very close to correct. What's both hilarious and sad is that someone on HN without access to the source code, debugging environment and internal QA tools probably root caused the bug, whereas the cable company's developers let it get all the way into production.
One of the reasons I've always been leery of regex. Especially since everyone I've seen using them tends to blindly copy an example from elsewhere and then bats at it until the test case passes.
1: https://en.wikipedia.org/wiki/MPEG_transport_stream