On a recent upload, I get a bunch of messages displayed:

Uploading current file for third_party/WebKit/LayoutTests/imported/wpt/encrypted-media/content/video_512x288_h264-360k_enc_clear_dashinit.mp4
Uploading base file for third_party/WebKit/LayoutTests/imported/wpt/encrypted-media/content/video_512x288_h264-360k_dashinit.mp4
Not uploading the current file for third_party/WebKit/LayoutTests/imported/wpt/encrypted-media/content/video_512x288_h264-360k_dashinit.mp4 because it's too large.
Uploading base file for third_party/WebKit/LayoutTests/imported/wpt/encrypted-media/content/audio_aac-lc_128k_enc_dashinit.mp4

There are actually 24 such lines. However, it is hard to notice the line "Not uploading the current file for ..." because it's in a large stream of messages. I had to wait for the trybots to fail to discover that this file didn't upload.

Since some of the steps display stuff in color (e.g. file sizes are red for original size, green for new size), it would be nice if the message was displayed in a different color so that it stands out.

Alternatively, repeat the message at the end along with a header like "==== Errors encountered ====". That would make it obvious that the file wasn't uploaded.