Why does interlacing not show in preview screen?
 

When I capture my old vhs tapes in amarectv the preview screen does not show interlacing. However, after I save my capture (lossless lagarith avi), the video file shows the interlacing. Is this normal or am I capturing incorrectly?

amarectv can do on-the-fly deinterlacing, maybe it's turned on for the preview? It hasn't been interlaced in the preview for me when I've used it but I probably went through and disabled anything deinterlacing related when setting it up. There are some settings for deinterlacing in the options.

Some capture software display fields not frames, Some like Vdub you can change the view setting to one field or blended fields ....etc, either way it is not going to affect the capturing so I wouldn't worry about it.