Using ffmpeg to convert file to same as another

Question

For some background, I'm making a webpage which adjusts the playback position in an embedded video when the user scrolls, so if you scroll down, the video will advance and vice versa. This works perfectly with one video file, but lags unbearably on another. It should be noted that I don't care about audio, it would be best if the files had none, in fact.

I don't know all that much about video formats, but I've learnt a lot in the last few hours!

So, this is the working video file:

ffmpeg version 3.4.2 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --disable-jack --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.11.101
  Duration: 00:00:20.38, start: 0.000000, bitrate: 5367 kb/s
    Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 5199 kb/s, 24 fps, 24 tbr, 12288 tbn, 48 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      timecode        : 00:00:00:00
    Stream #0:1(eng): Data: none (rtp  / 0x20707472), 164 kb/s
    Metadata:
      handler_name    : HintHandler
    Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s
    Metadata:
      handler_name    : TimeCodeHandler
      timecode        : 00:00:00:00

And here is the one which is lagging:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video2.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isomiso2avc1mp41mp42
    encoder         : Lavf57.25.100
  Duration: 00:00:19.20, start: 0.000000, bitrate: 7435 kb/s
    Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 7206 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Data: none (rtp  / 0x20707472), 225 kb/s (default)
    Metadata:
      creation_time   : 2018-07-22T22:58:04.000000Z
      handler_name    : GPAC ISO Hint Handler

As you can see in the second one, I've attempted to add a hint stream (via encoding.com) to improve the responsiveness of the playback as I've read it helps, but to no avail.

I'm wondering if some kind folks can help me work out the difference between the two files, so I can make it work nicely with both. Thanks!

EDIT

Here are the outputs of ffmpeg -i <file>.mp4 -f null - as asked for in comments:

• Working video
• Not working video

And here are the logs from ffmpeg -discard nokey -copyts -i <file>.mp4 -vf showinfo -f null -:

• Working video
• Not working video

Answer 1

video2.mp4 has sparse keyframes whereas video1 has one every 3rd frame, so convert it like so,

ffmpeg -i video2.mp4 -g 3 -profile:v baseline -movflags +faststart+rtphint out.mp4