Travelling nb i-15 approximately 4:13p.M. near apex exit n/e of vegas with dark clouds coming in from the north & north-west and sun was approximately behind me. where there is normally only the view of a mountain in the distance, i noticed a lite-coloured object of a great size fading in and out which i attribute to moving clouds around it and the sun reflecting off of the object when the clouds would thin. i watched the object for a minute + and felt it would disappear before i could get stopped (which has happened before). i stopped and made two short videos and took a couple of pics with an iphone 4. the videos do not show with clarity what i saw directly but i feel there is enough there that perhaps the images could be cleaned-up to tell us what this thing might be. i do not have the access or time to mess with this video but i feel it should be looked at. i have seen many unexplainable things in my 24 yrs in the area but have never been able to take a pic or video for my own credibility's sake :\ i would like one of your professionals to have a look next time they are in the area.