From a modern design perspective, integrating a video or animated image in the background is a great way to bring the website's theme together. The obvious problem is that it comes at the cost of performance of end users on the website. Mobile users may also not like the idea of downloading an extra few megabytes through their limited data plans just to load your company's page.
Fortunately, it is still possible to make the user experience better while keeping the load off of your server. The best bet may be to host the video on Youtube since Google's servers are much more stable than your local server. Youtube is also able to take the load off of your web server so that you may focus on other site resources.
Rendering videos that you want to add to the background to a smaller resolution is another idea to save on resource space. If you are going for a pix-elated design, you are allowed much more room for degrading the quality so that it matches this theme. With some CSS magic, the video may appear to be larger and higher quality than it really is. It all depends on the perspective and how it is applied to the page.
For more simplistic video designs, it may be better to scrap the idea for a background video altogether. You may apply web graphics, for which there are plenty of open source iterations online. For example, Codepen is an amazing resource project website with lots of examples that designers have worked tirelessly to create.
If the desired background video is relatively short, a simple animated GIF image may suffice. In general, animated GIF images will use fewer resources and have a smaller size than a video. For more information click here https://www.reddit.com/r/web_design/comments/94s8yb/trying_to_find_an_alternative_to_using_a_large/.