I live on the roof of a tall building and i have an interest in aviation so i am always outside watching planes at night and use flightradar24 to track them and i can spot a beacon 200 km away on a clear night. on 4 separate occasions i witnessed the same craft going from west to east. it had no flashing lights, did not fly straight or at a consistent speed and was not on radar. it was well below planes at 35000 ft and it even crossed paths with a plane, i estimate the craft was at about 20000 ft. i watched it with my binoculars for 3-4 minutes each time and could clearly see the craft, and the propulsion was mind boggling, i have a hard time describing it. the craft itself appeared transparent in the binoculars and seemed to hold straight and level, with an interior light that i could see all the time and blue and red lights at the bottom with a door and a row of windows, and when it accelerated the light became intense for a fraction of a second and it would appear to be out of control. after the quick blast of thrust it would settle down then it appeared to get hit from behind by it's own wake and it lifted the craft up a little bit. the only thing i can think of to describe is if you have ever been on a seadoo and give a quick shot of gas and let off, then the nose sinks a bit and your wave catches up and lifts it up, that is the best i can do as a comparison. the video seems to contradict what i saw in the binoculars, although the craft itself is exactly the same, it appears to spin and roll so fast and i don't see any red or blue lights and the internal light is only visible during the bursts of thrust that can be seen in the video. the orientation of the video starts at about 45 degrees and goes all the way up to 90 as it flew over my head and disappeared over my building. at the time, i was trying to keep the dot in the center of the screen and hope for the best. it just looks like a white dot on regular play speed, but if you zoom in 200% and slow down to 12.5% speed and it is still spinning fast but there is many clear still frames. in the last 20 seconds most of the good still frames show the bottom of the craft that is mostly flat with a dome on the bottom, the light is inside the dome. another thing i noticed in the video, and it also is in the slow motion video that i attached, there is one frame where it appears to eject something that glows for just one frame. this may be a star or a plane in the background but it caught my attention. i have seen many ufo's over the years, and have seen craft with similar flight characteristics but they were always at a really high altitude. i was excited the first night i saw this down low, then i saw it again the following night then there was a few days until the next sighting and then the next night i got the video, friday aug 2. i just want to share this, i know what i saw and after staring at it in my binoculars for 10 minutes nobody can convince me this is a weather balloon, and i had a lot of fun going thru the video zoomed in and advancing frame by frame. hopefully somebody else can find something i may have missed. the mp4 video is the original video, i also included a slow motion video and a few screenshots that were all taken from the original video.