You probably have a compatabillity issue, also ensure the files are not read only, look at their properties in windows and untick read only if it is ticked.

But I would say you have bigger problems, and to cut this short, you may need to use a video converter program to get them to a format supported by Movie Editor, below I have posted the spec for mp4 to successfully play or be imported into itunes, which is what you most likley have coming off your wifes phone, and thus may also be the reason Movie Editor does not recognise or want to play ball with them, am not sure about the files on your lg, but it could be something similar, in that they were encoded for yor divice, or are of the type that are generated to stream from the internet, I only ever came across one of these though that refused to play on my computer, but have had many mp4 files that played in everything refuse to play in a browser, just saying small hickups can cause no end of head scratching.

To work in itunes, MP4 video must meet the following specifications: it must be encoded as 540 kbit/s (minimum) MPEG-4 video (H.264) with an approximately 128 kbit/s AAC audio track or encoded as 1.5 Mbit/s (minimum) MPEG-4 video (H.264) with a minimum 128 kbit/s AAC audio track. If not, you will fail to import MP4 to iTunes.

So if the above standard is what you have, then maybe you need to convert it to a more suitable mp4 specification to get a Video editor to deal with it. Have a look at your files propertys in windows and see what you really are dealing with. Then perhaps a solution can be figured out.

Edit: you did not say whether or not you are trying to directly import these files from the devices you mention, or if you have them on your computer and are trying to import them from there, maybe if they were on your computer it would make things simpler.

Regards, john