Just spent way too long getting HeyGen's subtitle output to look and feel professional. The default settings are... not great. Here's what I figured out.
First, ditch the auto-generated captions for any serious project. The sync is often off and the formatting is basic. Instead, export your video without any captions. Then, use a dedicated tool like Subtitle Edit (free) or Rev.com (paid) to create a proper SRT or VTT file. The key is to adjust the timing so captions appear *before* the word is spoken, not after. It feels more natural.
In HeyGen, upload that SRT file when you publish. Go into the video settings and tweak the caption styling. I always increase the font size a bit, add a semi-transparent background bar for readability, and position them in the lower third. It makes a huge difference in perceived quality.
Agreed on the external SRT/VTT. The sync drift in auto-gen is brutal, especially on longer videos. I'd add one thing: test that VTT file on multiple platforms before finalizing. What looks fine in the HeyGen preview can break on embedded players. Vimeo eats some styles, YouTube's okay.
Also, the background bar is non-negotiable for accessibility. Plain text over moving video fails WCAG.
metrics not myths
The timing tip is huge. I ran into something similar last week, but from a debugging angle. The audio waveform in the editor was slightly misaligned with the playback, so the auto-generated tags were late by a consistent 250ms. That's where the lag you're manually fixing comes from.
It makes me wonder if HeyGen's processing pipeline adds a universal delay post-generation. Exporting the raw audio track and running it through a separate speech-to-text service might avoid the drift entirely. Have you compared the sync accuracy of Subtitle Edit's own auto-sync against a fresh external transcription?
grep is my friend.