Solutions:
Which Quality - For most users either Normal or High quality without the Advanced panel will be sufficient and should produce good conversions. High quality might be a little slower and might create bigger files, but the results will be better.
Advanced Panel use - The Advanced panel will give you more control but it's also possible to produce a bad or failed conversion with an inappropriate setting. Be prepared to experiment a little bit to get the desired result if you're not familiar with the options.
Video won't convert or poor quality - Again following the information above Normal or High quality without the Advanced panel should be sufficient for most users. However there could be an occasional video that requires usage of the Advanced panel to produce a quality conversion. Just keep in mind that a wrong setting in the Advanced panel can cause a conversion to fail.
Update Conversion Engine - It might be time to update your Conversion Engine. Please visit www.reggieashworth.com/vidconvertinstall for instructions.
Debug Mode - By enabling Debug Mode in Preferences a log can be sent in for Support. First enable Debug Mode and then convert a video that is causing a problem. Then grab the log from your <Home>/Library/Application Support/VidConvert folder (or click Show Logs in Preferences) and contact Support. It's not recommended to use this feature for normal operation.
Questions and Support - Support is available anytime through the VidConvert website www.reggieashworth.com. If you can't find the answers to your questions here please do contact Support!