From what I can see , according to the info you provided above, your finished video is in wmv (codec) format, which is the format developed by MS years ago. The finished recording is 1600 x 900 px resolution. That's a pretty good resolution and should show detail well. Only MP4 1080p is larger, amongst the common formats. A 17.1 Gb wmv video must run for hours. What is the full time on your vid, in hours and minutes.
Sorry for late reply; flu bug running rampant here........
regards
Mike
This would makes sense regarding his video size. WMV files are not necessarily the smallest files around and don't compress well overall. They came in second, I think to the famous AVI format which has been around for so long. If he can convert the WMV (Windows Movie) to MP4 then he's all set. Windows Movie Maker, which is still available from Microsoft as Windows Essentials Live http://windows.microsoft.com/en-us/windows/movie-maker will do this quite well for free.
Good luck on the bug... You surviving?
John
PS off topic totally: Check out the Screenshots WIP thread - pics of treeless HT&W.