Use a well-designed BNC footprint to ensure the BNC's signal landing pad achieves 75-Ω characteristic impedance. BNC suppliers usually provide recommendations on BNC footprint for best results.
Keep trace length short between the BNC and SDI_OUT1±. The trace routing for SDI_OUT1+ and SDI_OUT1– should be as symmetrical as possible, with approximately equal lengths and equal loading. The same is true for SDI_OUT2+ and SDI_OUT2–.