Exporting as PNG sequence is the recommended was to get transparent backgrounds.
You can try other ways such as you have although the results may not be ideal.
Recommended for people that use Premier. What about for people that do not use premier?
Premier is one tool there are many others that also allow importing PNG sequences from premium tools such as Premier to Free tools like Windows Movie Maker.
What tool are you using?
I use Pinnacle Studio. I can import the sequences as images but I need to set the image duration to .001 before adding them to my timeline. And .001 is still too slow. WMM imports PNG sequences? Like Premier? I just used Premier and it is quick to import them due to the "Import sequence" checkbox. I just don't have that with Pinnacle Studio.
With Windows Movie Maker you can import an image sequence.
Use the add Videos and photos option
Open the folder containing the images, select them all to import them.
You will need to edit the project via the edit option and change the duration based on the FPS you used to produce the sequence.
e.g. divide 1 by the FPS setting you used so 25fps = 0.04.
I know you can export to PNG and open them in Premier and all that. This is too long and complicated. It takes over 8 minuites to render a 1 minute long video and I don't use Premier.
I have tried setting the background a nice chroma green. Export as a video. Then, in your NLE, just use chroma key to remove the background. The hands don't look great chroma keyed. There is a fuzz around them, but the text looks really crisp. The chroma is really a 1-click option since the background is uniform green.
What are you guys doing?