Как по Английски будет sobre la marcha

phrase

While in motion or progress.

Примеры использования:

Producers were able to schedule the day's olympic coverage on the fly

idiom

If you say that you would like to be a fly on the wall on an occasion, you mean that you would like to hear what will be said or see what will happen while not being noticed

Примеры использования:

I'd love to be a fly on the wall when those two get home!, a fly-on-the-wall documentary