This is my first post so, hello to all 
I’ve been trying to find a way to render a 4K video at 60fps with Alpha, and still follow the format rules on Envato… and I haven’t been able to do so.
I guess my question is, A: is there a way in doing so and B: why isn’t there an option to upload image sequences?
To me it makes much more sense to upload an image sequence which is lossless and smaller in file size, than to compress and send a huge video.
You mean uploading a preview video? You have it backwards. A lossless png or tiff image sequence is going to be massive and not something you want. I don’t know how long your image sequence is but just compress to a couple megabytes with handbrake or something.
You could always render out a black and white matte for the clip rather than encode an alpha channel. WIll save a lot of space.
Thank you for the reply Luxai,
I was referring to the final product, the files the client gets.
I’m still not sure if it’s allowed to upload image sequences, or if there’s a way to render such a video (4K, 60fps with alpha) and keep within guidelines.
About the file size, my png sequence is 600 frames (10 seconds at 60fps), 240MB when zipped
I was able to rendered with alpha channel
here is a demo
Unfortunally it was rejected. I noticed that on bsplayer the snow is squar and very uggly. If the reviewer saw what I saw in bsPlayer then maybe that’s why was rejected.
So the ideea is that it is possible to export …
Oh that’s a really good snow simulation, it looks great!
At 30fps it’s possible, yes, but what about 60fps?
I rendered at 60fps but not 4k
why do you need 60fps for a preview?
Preview is a preview - it’s for visual purpose only. To get the style and overall motion.
Whats the point in uploading 4k or 60fps ?
Why does everyone keep going on about previews?! 
To the OP… it looks really good, but there’s quite a few snow clips already, so it doesn’t really bring anything new to the table. I my opinion, anyway.