I think it's fine to see for yourself what the quality looks like with the Game Capture HD, but odds are that it will look pretty terrible, In a perfect scenario where it locks onto the signal well and doesn't drop frames (which is unlikely without some type of TBC as Lordsmurf mentioned), it will still throw away half of the data (will likely blend or discard half of the video information taking the interlaced signal and saving it as progressive) and it'll encode it to blocky/lossy/low bitrate MP4 format with poor audio quality at the time of capture.
I found a video on YouTube below showing just how unstable this specific card is for this task, see below:
https://www.youtube.com/watch?v=35jhY4EHE98
It'd probably improve to not as visibly glitchy with the addition of an ES10 or ES15 as Lordsmurf pointed out which will stabilize the signal to some degree, but you're probably still better off using a different capture card altogether that can capture interlaced video more easily.
Based on that demo above, it is apparently much worse at tolerating unstable signals than the regular Elgato Video Capture which is marketed for VHS capture. That still suffers from the same quality issues, low bit rate, and blocky MP4, and poor quality audio encoding mentioned above, but it'll at least watchable on a small screen. You're basically trading all of that for small file sizes and simplicity of use when used with the original software. Alternative capture software like
virtualdub might allow it to capture in higher quality so no harm in seeing if it shows up as a useable device in
virtualdub, but based on that YouTube video, I don't think it is going to lock onto the signal well regardless of capture software used.
Back to your original question - My guess as far as why there's no video viewable is that you could have the wrong input selected in the software as it may not autodetect which input you are using. I'd also do your initial testing with a stable signal like what the Game Capture HD is meant for - something like an older game console that has composite output. If you can't get it to display that (which is a much more stable, digitally precise signal), then there's no way it'll display the VCR's output, so I'd start there to at least see an output and make sure composite input is configured correctly. Could also be that the drivers are broken in the operating system as well.
