Silicondust support said I have low signal levels, and when I tried boosting the antenna amplification, it was high RF signal levels, which means that it's just amplifying noise.
Since I planned on using this for both OTA and cable, I hooked up my cable to Tuner 1 and scanned in channels on QAM256. There's not a whole lot of unencrypted Comcast, but some channels showed up. However, when I go to "Watch Live TV", it can't lock in on a channel (same error as when I tried viewing with only antenna hooked up to Tuner 0). One other time I tried, it said something like both tuners were set to start on the same channel, which is weird since there is no starting channel for OTA since it failed to scan in any, and QAM is set to start on 247 (which is a 24 hour local news channel). The other thing is that whenever I exit out of Myth setup, it complains that "the tuners are set up to start on channel 3, which doesn't exist", and when I click the button to autofix it, it doesn't, and so I then click on the button "ignore - I know what I'm doing".
Also, does SchedulesDirect have listings for my local Comcast or just OTA content?