What the others have said is right on. In general, it's going to be hard to sell snow with summer shots. When making advertising content, you've got to show people what you want them to "buy". Also, I would stay away from fancy overlays and graphics unless they are really clean and high quality. Otherwise, they cheapen the production. Also, you don't want too many things going on at once. This will confuse the viewer because they don't know what to look at, and it will distract from the main point of your video. If you look at professional video, it's very often just footage, possibly with text overlaid. Also, try to slow down and smooth out your camera moves. Another thing that could really boost the quality of the video is properly color correcting and grading it, to make the colors look less washed out.
