Spawned from bug 1114805 comment 9 Currently, we assert if we attempt to perform any operations on a negative time value (in particular seek). start and end time position are initially set to -1 which means "no value/not set". There's no guarantee that a media won't have a negative start or end value. The only guarantee is that the duration is positive. We should handle this case, and don't assume that a time can't be negative
bug 1179110 will fix this issue.