Ellipses are over-used in scriptwriting in our opinion, particularly in dialogue. The only case we know of to use them is when a character's dialogue is trailing off, for example if they move off into thought or are passing out or the like. Any other valid uses?
And I think it's easy for either to be overused. Instead of using (beat) within dialogue, I like to put in a brief action line, e.g., "Jamie pauses, searching for the right words." That's not necessarily the best example, but I prefer that sort-of thing to "beat" because it achieves that same effect but gives the writer an opportunity to give more insight to character and/or advance the plot (if only a bit).
That's a good point. I think, if you can, use scene direction instead of falling back on lazy tricks to dictate the dialogue. If I was an actor, I wouldn't want a the same "trail off" cue for every line.
And it's best to let the actors do their job.
They are helpful.
The trend I've noticed in reading professional screenplays of produced studio movies is that they tend to use the beat as a tool more than ellipses. I'd say it's easy for either to be over used, but if you're showing a pause of a break in dialogue, either cut in with scene direction or
(beat)
for a more compelling effect.