Howdy,
I would like to offer my services to help with recreating your banner in swf format with appropriate size under 50kB.
I have a vast experience creating Flash/HTML5/GIF banner ads and even more importantly downsizing the creative for the banners while making sure it remains as high quality as possible. With your banner in simple color scheme this is very easy job for me. I am confident I can recreate your banner precisely.
Please check my profile page here: https://www.freelancer.com/u/SueKocian.html for a few samples of my work and also testimonials of previous clients. I guarantee 100% satisfaction.
Please allow me a few questions. Is the GIF file you included a representation of how you want the final animation to look like? Is there a reason why you want the banner to be in SWF - flash format? Would you be interested in HTML5 version instead? As HTML5 banners are viewable across all the devices and services like Google AdWords, DoubleClick...etc. all support them if guidelines are followed. I specialize in creating HTML5 banners as well - either in Adobe Edge or Google Web Designer. Do you require a clickTag to be inserted in the banner? Do you need specific ActionScript version used?
Please don't hesitate to contact me if you'd like to discuss further or have any questions, I'd be happy to hear from you.
Have a good day,
Sue Kocian