Thanks Stefan for your test file. In Cinelerra-GG, for what I are seeing, the problem is not cutting the video in the Timeline; the video also freezes without cutting anything and playing frome some points. Your video use long GOP (max 250): there are I-frame, B-frame, P-frame. The I-frames are at: I-0001, I-0220, I-0447, I-0697, I-0913, I-1163 and I-1342. Like me, you can do an easy test in Cinelerra-GG. 1. On the Timebar, in the Main Window, change the display from "Frames" to "Hours:minutes:seconds: frames" (use Right Mouse Button on it, see https://cinelerra-gg.org/download/CinelerraGG_Manual/Insertion_Point.html). So you can see "Frames" instead of "Hours:minutes:seconds: frames". 2. Add two labels at 913 and 1163 (you can use "Go to" tool) 3. Move the Insertion Point at 930, for example, and press Play (Numpad-3): it should work fine. 4. Move the Insertion Point at 850, for example, and press Play (Numpad-3): video freezes until it reaches the I-frame (at 913). The same happens for the other I-frames. It seems a problem around some B-frame and P-frame. As Andrea_paz said, the MKV codec format can be problematic if the encoding is not done well by the program (OBS?). I don't use OBS Studio, so I can't try it using other output format codec. Possible solutions: a) As told by Andrea and Phyllis, using Transcode's Cinelerra-GG or an other Convert tool. b) In OBS Studio change the output codec, for example TS (Transport Stream), MOV, MPEG2, or ???. Because your video is yuvj444p h264 High 4:4:4 Predictive, in OBS can you change any parameters of that? For example to yuvj420p and try? IgorBeg PS: other Users have many problems with MKV files from OBS Studio using Commercial NLE (LightWorks is one of them)