Just drag & drop a file if it is just one file like animated GIF, APNG or WebP.
2. If you have no images or videos with transparent backgrounds but just with green or blue backgrounds, you can use the Chromakeying filter in Honeycam to make green or blue backgrounds transparent.
3. Now just click the Save button and you will have the video with transparent backgrounds!
Click the Save button and select the format as WebM.
You can check how it looks on the browser by clicking [View in browser] button.
For your information, you can choose VP8 or VP9 for WebM option. VP9 outperforms VP8 on compression ratio but VP8 is more compatible with diverse browsers.
Please be sure to check your WebM video on the system where it will be played because there are some browsers that do not support WebM.
Please be careful! Most video players do NOT support videos with transparent backgrounds! Please use browsers like Chrome, Firefox or Safari to check it.